I tend to be a rather blunt person. It's not much of a problem in real life, because the tone of my bluntness is not malicious or rude, and I avoid things like name calling or general insults, but on the internet I find that people impose their own tones on your words and interpret what you say with the tone they want to give you(ex: if they're insecure they're more than likely going to assume you're ragging on them)... as a result there are a lot of people who get butt hurt over nothing. So as a general rule I tend to not give people online advice unless they ask for it.
Example of what I mean, say someone posts a picture and it has wobbly lines.
Me: Your line art could be smoother, you may want to try a stabilizer, or practice making faster strokes that use your whole arm.
Some people will decide that this comment is helpful, some will decide I'm making the biggest attack on their lineart and I just can't appreciate their stylistic choices. Some people would argue that I should put that feedback in a compliment sandwich, but honestly I find that when you sugar coat your feedback too much, the person misses the point.