Depends on the culture. Some countries have a much less overtly polite culture than the US or UK, and direct criticism is expected and welcomed. The UK is part

Depends on the culture. Some countries have a much less overtly polite culture than the US or UK, and direct criticism is expected and welcomed. The UK is particularly bad for this. Depending on tone and context "I'll consider this and get back to you" can mean "I think you're an irredeemable idiot and this is the stupidest thing I've ever heard." Or it can mean "Interesting, let's think about it." This drives some Europeans working in the UK insane because it's so hard to tell what people really mean. It's a two axis problem. Bluntness is on one axis, and good/bad faith are on the other. Blunt good faith criticism can be fine if it's culturally appropriate. Bad faith criticism is never appropriate, even when it's wrapped up in politeness.