I've noticed the same thing with some bike shops I've dealt with as well and while I can appreciate their interest in wanting to sell me a bike brand they carry, there's no need to trash those they don't. I went to a shop once that told me Cervelo's bikes have a lot of bottom bracket failures and I should stay away from them, something I had not heard of from any good source. I haven't read of any issues with BMCs frames, of course there will always be defective bikes etc but not anything different than you'd find with any other bike manufacturer.