IanBicking analyzes it :
Aside : I listen to a stack of pirated music on my machine. I'm not ashamed of this because I don't think that music is, or should be treated as, a kind of property.
But ... I do occasionally buy music ... more or less always on BandCamp when an artist manages to inspire me to want that kind of relationship.
And I document my listening on LastFM where I can see what I'm listening to most heavily at the moment.
Now if anyone were in the position to guilt me into paying for music, it would be LastFM. If LastFM had a little "you like this? donate to the musicians via PayPal" button next to my "most listened" tunes of the week / month etc. I'd probably, retrospectively, bung a couple of quid to musicians I was really feeling that month.
It would catch me at the moment I was feeling most well-disposed towards the artist, and wouldn't make me feel I was buying into a bogus notion of "music as property" (attempts to do that tend to fail).
OTOH buying the "next" piece of music by an artist for whom I love something I already pirated, is almost always a disappointing experience. Few artists are good enough to make me love them consistently. So even when I love something they've done, buying from them is a negative experience.