if youre smart youl run an anti-p2p filter. but that still doesnt keep the cable company off your back, if you blocked their ip then you cant connect. if they looked at what i download all they will find is a bunch of unsigned black metal bands who only want to get their message of hate and evil out and dont give a **** about the means. i only share enough to keep my ratio at 1, and on emule i just leech. its important to keep your share folders relitively empty too, just keep what youre downloading or seeding, and move it when youre done. if youre really anal about it, go find a good proxy, as thats the only way to hide your ip.
as for how they detect. piracy is policed 100% by the organizations whos copywrites are being infringed upon (directly or through investigators, or cartels like the riia). i guess they could have bots that seek out any torrents or hashes of their stuff. for p2p they just look at peoples share folders and hit printscreen. this is whe whole of their evidence. so its important to hide your shares from the public. if you want to release (and if you do i salute you) your gonna have to pay for a high throughput proxy service. another technique for riaa-avoidance ive seen emerging is the use of password archives that require you to go to a forum and ask for it. its not foolproof but if your case is too hard to proove, and if the person looking is payed by the bust, there gonna go after easyer prey.