You're not the first person to say that about a Basset Hound. I've never had one, but that is their rep.My other dog is a 10 year old basset hound. I swear he's as dumb as a box of rocks.
I did have a dull dog once, and it is frustrating. To make matters worse, she tried very hard and was extremely sensitive to my attitude. If I started doing a slow burn, she would immediately shut down. There was no way I could put a happy face on if I was feeling stressed. She always sensed it.
The only thing I can tell you is to muster your self discipline and control your emotions, don't press a training session if things are not going to end on a positive note, and always end a session on a positive note. That may mean starting a session and, as soon as you see it's not going to go well, going to something the dog can do well.
The dog controls at least 80% of the training process.