Why dealers disparage certain products?

Got it @hilde45 we should all think like you and go our merry way. So much for opinions and discussion. 

I buy what I like if a dealer dislikes I move on to another dealer.Many dealers bad rap things they do not sell.

Maybe if your competitor disses your product on the internet?

 Or posts a false review of your restaurant? There may be times to attack a competitor, but it is not without peril. 

I trust my local store enough that if they say something negative it holds weight with me since they don't make a habit of it and at times I agreed from my own experience.

It's always been a gripe of mine way back before I sold audio products myself. I always disliked the way salesmen would cut down the competition only to find them selling the offending product a few months later.