i honestly think it really depends, and this is coming from someone who does buy a lot of store brand. Publix store brand deli meat is as good as anything else, but on the other side of the coin i've had even name brand mouthwash (Crest pro health) make my teeth look brown. only found out later it was a known problem with one of the ingredients. literally Listerine total care is the only OTC i can use.
caveat emptor i suppose