It also depends on the approach. I, personally, dont reply when I get tons of "hi can you check my track out plz" and link to a soundcloud page with progressive house etc. And some people really have trouble with proper email writing and think that you're their possession to use when it fits themselves.
Facebook is a perfect platform for public terror of that sort, I'm never online on that chat these days, it used pops up people every day with no greeting or anything just a "how do you make this and that sound". Stuff like that ticks people off. With that being said I personally try to be as public as possible even though I miss the good old days where I only was a black white photo with bad contour a name and music on some label sites.