This is irrelevant to me unless they 1) do so while describing specific flaws that I'll actually care about, and 2) every honest seller is affected by it.

It probably sucks to be an honest seller affected by it, but I've yet to find a situation where I have unable to find a product I'm happy with, so clearly they're not doing this often enough to affect me much.

I've seen 1 star "reviews" on products that directly reference a specific competing product or seller that the "reviewer" recommends instead. You'd think with all of Amazon's computing power they could detect obvious scams like that.