Commonality

Ok. Is it just me? Maybe it is my freaky snobbery. But I hate it when shopgirls or shopboys or waiters or waitresses try to recommend a product to me on the basis that it's their favourite too. I mean hello. Why should it make any difference to me that some total stranger, with nothing in common with me, and who frankly I don't really think I'd like anyway... Why would it make any difference to my purchase decision that they like the same thing? Or maybe they're just taught to say that.