Like my husband says all the time, opinion is like an ass (sorry for my language), Everybody has one. I guess you have to explore, observe and be careful what is right for your dog and what is not agree with.
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from
www.dogfoodproject.com Myths about Feeding and Nutrition
Dogs should not be fed table scraps
One of the most widespread myths the manufacturers of some (mostly poorer quality) products perpetuate. They claim that table scraps will upset the balance of the commercial dog food, but just like like humans, dogs do not require a diet that provides uniform meals every single day of their life. Dietary deficiencies do not appear overnight but need a long period of consistently poor nutrition to develop.
Dogs will also not automatically get fat, learn to beg at the table, or refuse to eat their own food just because they are fed table scraps. They will, however, do those things for various other reasons, like being overfed, not trained properly or just plain spoiled.
It is important that you do not feed junk food, candy, items that contain a lot of artificial ingredients, high amounts of fat, salt or sweeteners. Leftover meats (or meat trimmings), pasta, rice, oatmeal, baked or steamed potatoes and especially fresh, raw or lightly steamed vegetables and fresh fruits are healthy additions to a dog's commercial diet. Moderation is the key and of course you need to substract the amount of foods you supplement from the total daily ration of dog food. Carbohydrates must be processed in order to be digested by the dog. This is either achieved by finely grinding, pureeing or mincing, or gentle cooking or steaming - but not at excessively high temperatures or for long time periods.
Mixing different dog food brands will improve my dog's diet
This misconception seems to originate from dog owners feeling guilty about the type of food they feed or those who follow their own ideas for "improving" their dog's diet without doing any research. Every brand of dog food is following a specific formulation and philosophy developed by the manufacturer. They are all formulated to supply a balanced amount of nutrients in a ration of a certain size, based on the body weight of the dog. When mixing different foods you run the risk of your dog getting either not enough or too much of certain nutrients. Last but not least, if digestive upset occurs, it's going to take so much longer to figure out what exactly caused it compared to just eliminating either the commercial food or whatever extras were fed recently. If you want to offer more variety, stick to one line of food of the same brand at a time and rotate between brands every few months. Supplementing the dry food with fresh, "live" foods like vegetables, fruit, yogurt, meat or a bit of canned food is also safe and healthy.
Dogs should not be fed (raw) eggs
The main argument is that the enzyme avidin contained in the egg white destroys biotin within the body. Fact is that the egg yolk supplies more than enough biotin to make up for this loss. Salmonella are another concern, but dogs with their significantly shorter digestive tract are much more resistant to these bacteria than for example humans.
Dogs should not be fed cottage cheese and yogurt
This incorrect information originates from sources that do not take into consideration that not all dairy products contain high amounts of lactose and that not all animals have trouble digesting them. Just like some humans, some dogs do not produce any, or not enough of the enzyme lactase, which is needed to break down lactose. This is a condition commonly referred to as lactose intolerance.
Cottage cheese only contains minute amounts of lactose and yogurt is generally tolerated well and rarely ever triggers symptoms. Cottage cheese is an excellent source of calcium, phosphorus, protein and vitamins; yogurt is a good source of calcium, protein, potassium and magnesium and (if products with live cultures are fed) can supply beneficial bacteria like for example Lactobacillus acidophilus, Lactobacillus bulgaricus and Streptococcus thermophilus. It also helps to soothe upset stomachs in sick animals.
Only the plain versions of these products should be fed to avoid unecessary sugar intake. If you want to feed cottage cheese, low fat and low sodium varieties are preferable.
Dogs need a food product appropriate for their life stage
This is what pet food manufacturers want you to believe, but it is just a way to secure their customer base early on and increase sales. The more items in a particular line of food, the higher the visibility of their product on a store shelf - an of course the more likely people are to buy and stick with the brand through the whole life of the animal. Fact is that a food declared as suitable "for all lifestages" will feed a growing puppy just as well as a lactating bitch, an adult or a senior dog - just the amounts you have to feed will change. Puppy and senior food is often more expensive than the regular type of food of the same brand, yet does not differ much in nutritional value. Compare the guaranteed analysis and ingredient list.
Further, puppy food can cause large and giant breed puppies to grow at maximum rate, which is not healthy for them. A slower, more even growth results in far less risk of orthopedic problems and a healthier adult dog.
All commercial dog foods are bad
A very general statement with little credibility and even less proven facts to back it up. Anyone who puts even just a little time into research will see that the quality of products varies just as much as the ethics and philosophies of the manufacturers who make them. It is true that there are foods of good, average and downright bad quality, but there are companies who take great care in choosing the ingredients for their food.
A dog's digestive system is not able to fully digest and utilize grains
This one at least has some truth to it. Compared to herbivores a dog's digestive tract is much less specialized for digesting grains, or carbohydrates in general for that matter - especially in their raw, unprocessed form. However, dogs are not true carnivores but opportunistic feeders and can digest and utilize the starch from grains in dog food that has been converted by the cooking process. Digestibility depends on quality and type of grain used: rice (72%) is for example more digestible than wheat (60%) or corn (54%). Dogs can absorb the digestible carbohydrates from rice almost entirely, of the other grains about 20% are not absorbed. Indigestible fiber from grains contribute to intestinal health.
A dog can only truly be healthy if you feed a raw diet
This is another factoid never backed up by scientific proof. Any animal can only be healthy if its diet supplies all essential nutrients in sufficient quantities. If even just one of them is missing or not present in at least the minimum required quantity, the animal will start showing signs of malnutrition, eventually become sick and die. Some deficiencies don't take very long to become apparent, others develop over a long time before the critical state of health becomes obvious and some diseases are even caused by excessive intake instead of deficiency. The key to a healthy dog is not either raw or processed food, but an overall complete and balanced diet.
another opinion on what to/not to feed 1. 
