Go to Pirate Bay and search your band's name.
- Zero search results = Basically nonexistent.
- Torrent(s) with 50+ seeds = On the right track.
- Torrent(s) with 500+ seeds = Limousines and vodka.
I'm sure by now I've already offended someone, but I assure you it's an oh-so-effective indicator. On Pirate Bay, SE = seeds, LE = leechers, and both are sortable columns towards the right side of the PB interface. A seed a.k.a. seeder is someone who has the entire torrent. A leecher a.k.a. downloader is someone who has part of it. The more seeders there are, the more exponentially available the torrent becomes.
The number of seeds and the overall size of the swarm are the most defining metrics. Browse Music (or specific genres) and sort by the number of seeds to see what has the most. In the screenshot below I've done it, and as you can see it paints a pretty good picture of what's hot right now.
Less than an hour ago when I took this screenshot the #1 music torrent, My Beautiful Dark Twisted Fantasy by Kanye West, had 6,993 seeds. Now, minutes later, it has 7,528 seeds. With that many seeders, the downloads are like lightning—approx. <2 minutes for the entire album. For perspective, compare Kanye to the #1 movie torrent, Inception (2010) which right now has over 20,000 seeds. I can't remember ever seeing a torrent with that many seeds. P2P is anything but dead. The surprise to me here was that Mumford and Sons are the sole rockish act as hot as the mainstream mayhem.