I buy my music from there, if there isn't a more attractive offer from the label itself (Sometimes Nuclear Blast has a killer offer of limited edtition vinyl in superb colors.... I can't ever pass that up...)
I've had no troubles buying LEGO sets (nothing overly fancy... the low-end "city" stuff), and I sometimes buy used books from third party sellers there as well. But I am realistic. Seeing something that otherwise costs $500 for $99 is part of my job as a savvy customer to avoid, even if it says "Amazon Choice". (It's a marketing label, not a UL seal of safety.)
It's all in how you shop, really. If there are people out there who think because Amazon is on the Internet that it's somehow magically safer and policed properly (a worldwide retailer, to boot)... they should really do their homework. If they don't, then they deserve what they get indeed. Wal Mart has been caught selling counterfeit goods before, and sometimes unsafe things. It's all about awareness...
To me, boycotting a giant corporate behemoth because they can (and do) sell counterfeit and possibly unsafe Chinese knockoff goods is like cutting off your nose to spite your face. But to each his own.... I don't begrudge people's principles... I just don't find boycotts very effective.