In person, I will tip the busker/artist/etc if I was paying enough attention to notice (sometimes a high bar), and I liked their work enough to go out of my way to hear/see more (which is a fairly small fraction -- many cause me to flee), and I have reasonable units of cash with me. I will pretty much never strike up a conversation with a stranger. I will occasionally buy a CD or similar. I'm more likely to tip a solo busker than a performer at a street festival or similar, which now that I'm thinking about it seems incorrect. Also now that I'm thinking about it, at a street festival often the things I like best are for sale, and I don't necessarily want/need a thing to take home, but have no idea of the etiquette for "I am very glad this nifty thing you made was here for me to admire, but I do not have a proper home to offer it".

Online, there's vastly more stuff, the overhead of 'look for more' is much lower, the overhead of tipping is higher (in both my time and paypal fees), and tipping isn't so anonymous. I think I tip online more often overall but for a much smaller fraction of what I see/read, and the selection is a little more arbitrary. I am unlikely to comment unless I have something cogent to say or know the artist.

I mildly prefer music, story, and 3-d arts over 2-d arts and dance.

I'm aware (and thank you for the training) that not-particularly-cogent comments are still appreciated by at least some artists, but lurker inertia is still pretty strong.