I'll admit, at the store I work at, there are some customers that I "stretch the truth" with... I'm guilty of telling customers that they cannot put ANY other fish in with their betta. Simply because I know some of the regular customers that come in only half listen to what you are saying, and if I were to tell them that it is possible to have a community tank, that would be all they would hear, and go out and buy too many fish and not have a back-up plan. Then they would come back to me complaining that I told them it WOULD work (even though I said COULD), and blame me for all the fish deaths in their tank. Not worth the trouble, so I tell them bettas like to be on their own, which is mostly true.. lol
BUT if the customer proves to be willing to listen, I will tell them all that I know, and will help them as much as I can to set up a nice community tank.