We have a PETCO store in our town that is clean, organized, and attempt to be helpful in-spite of misinformation. You seldom see dead fish and the stock is less than quality. It's a bit of a crap-shoot, at least they honor their guarantees. I do buy from them on occasion.
We do have a PetSmart about 35 miles away and I haven't been in the store in 3 years. The last time there, several dead fish in all tanks, bad information, and poor attitude sales persons made me decide to never go again. It was the worst experience I have had when dealing with a chain store.
Any store is only as good as the management regardless of the name on the outside of the building. To lump all stores into the same category because of their name isn't fair to the good ones.