People confuse directness with being an asshole. If your results suck, saying they suck isn't being an asshole. If you feel that something is horrible, sugar-coating it to make sure you don't hurt someone's feelings is unauthentic.
Here's the difference...
When someone says "your product sucks, throw it away" .. with the INTENT of causing that person to feel bad, thats being an ashhole.
If you tell them that their product sucks because you genuinely feel that way, and you're simply communicating authentically, then you're not being an asshole, you're being authentic.
Here's how you can tell the difference. The former in that example get stuck at best in middle management in low-quality companies... the latter finds themselves at the top.