False. I think donk betting gets a bad reputation because many recreational players do it with no real plan, but that doesn't mean the play itself is bad.
Like most poker actions, it depends on the situation. On certain board textures, especially when the caller has a range advantage or a lot of strong draws, a donk bet can be a very effective strategy.
The problem isn't donk betting—it's donk betting every flop regardless of position, ranges, or board texture. When used selectively, it's a legitimate weapon. When used automatically, it's usually a leak.
So for me, donk betting isn't a sign of a recreational player. How and when it's used is what matters.