BitComet (and BitLord, which is a clone with ads) is banned for numerous reasons by many sites, seeders and traders, mostly for violating the sanctity of torrents marked as private.

My reason for banning BitComet (heretofore: BC) is different, and involves the behavior of the client while I am initially (AKA "super-") seeding a file. BC promotes itself as having faster download speeds than other clients, and accomplishes this (or at least tries to, before many peers kick/ban it) by repeatedly disconnecting and reconnecting in an attempt to receive blocks faster.

Two reasons why this is extremely bad for a torrent:

1) If the BC user is a leech who throttles his uploads, he will be able to grab more blocks from other people than he trades in return, specifically, very rare blocks. If he then logs off, those blocks are lost from the torrent, and must be reseeded. During initial seeding of a torrent, many clients (such as Azureus, uTorrent and BitTornado) keep track of how well the recipient of a block re-trades it, and dole out new ones accordingly; BC attempts to end-run this by "cheating", reporting 0.0% file-acquisition after re-connecting in order to be granted priority status, then it reports its "peer ul" speed as being grossly higher than it actually is in order to fool other clients into continuing to send it more blocks (when they eventually refuse, then BC disconnects and reconnects, starting the cycle all over again).

2) During reseeding of a languishing torrent, if 99.98% of the file exists in the swarm, only the few missing blocks will need re-seeding. However, if at any given moment several of the peers are BCs playing the disconnect/reconnect cheating game, not all of the swarm will be visible and the actual full percentage known. So, instead of 99.98%, it could be much, much lower, meaning that the seeder will waste a large amount of time and bandwidth re-uploading blocks that already exist in the torrent.

The problems of 1) and 2) compound each other: BC will steal an inordinate amount of initially-seeded blocks, and then conceal (by disconnecting) the fact that the torrent swarm has those blocks.

3) Most "regular" torrent-traders already know why BC is bad, which means BC users who do appear are likely to be noobs; noobs are usually slower traders (often still using modems) and using BitLord because it's heavily promoted on many of the lamer hosting sites (I will *never* host a torrent at a site which advertises BitLord). What this means is not only are the torrent's rarest blocks in possession of a cheating client, but that the peer is likely to be VERY SLOW.

-- There's nothing more pathetic than opening up a torrent to find nobody in it but a half-dozen or so BC peers all desperately attempting to leech from each other, and the whole thing is completely stalled because no one will share, even though 100% of the file is in the swarm.

BitComet is a BAD program: Kick and ban it aggressively in order to EDUCATE people not to use it. There are plenty of very good FREE torrent-trading programs out there, and there's no reason to use one which will invariably get your IP address banned by A LOT of other people just because you believe, erroneously, the hype that you'll get faster DL speeds (hype that's true only if nobody bans you because your client is a cheat).

How much do I hate BitComet? I hate BitComet so much, that even if new versions which don't cheat appear, I'm going to keep banning it anyway -- because it's tainted as a *franchise*. That, and I'm not interested in watching every single BC peer to see which are cheating and which aren't.

================

How to kick/ban BitComet:

-- First, obtain and install PeerGuardian (you should be using this anyway).

If you use Azureus, it's easy: Select a BitComet peer and right-click and kick/ban.

If you use BitTornado, you can't, so don't initially seed with BitTornado unless you don't care if it takes you 25-50% longer to fully seed a new torrent (with lots of BC peers) to the point of it being able to continue on its own.

If you use uTorrent, right-click a BC peer who's "cheating", and select "Log Traffic to Logging Tab". After awhile, you'll see his IP address in the Logger tab. Create a new list in PeerGuardian's List Manager (I name mine "leeches"), open it, add, put "BC" in range, and enter the IP address in both the starting and ending IP fields. Save & close the List Manager.

I prefer banning IP addresses in PeerGuardian because then it's easy to uncheck the leeches list when I'm downloading (I haven't any problems *receiving* blocks from BitComet peers, even if the amount they may send versus other clients is comparatively paltry).

Final note: Some leeches hack their BitComet application to report itself as a different client. They cannot, however, hide the repeated disconnect/reconnect behavior. If you see anyone doing this, kick & ban them whatever their reported client.