You should assume that all ISPs are using deep packet inspection to see what you're up to. This doesn't mean that they are tracking you. Their algorithms would need to optimize their routers based on the type traffic flow for one thing. But yes, they can certainly look at TOR traffic and recognized it as such. But it's encrypted and thus of limited use to them. Remember that ISPs are not policemen in the West, that is LE's job.*However** It is always a red flag to use TOR from the perspective of LE.* If you are the only person in your area using TOR...* If few people in your country use TOR...So, people in different geographical areas, should assume different levels of paranoia about their security situations.Using TOR in an area of higher population density is always preferable.By utilizing a bridge, you are able to get around this possibility of TOR use discovery. This is not difficult to do. Read the help files supplied with the TOR package. To take it to the next level, you should use a private bridge. i.e. a bridge you've setup yourself exclusively for you.TOR traffic, unless you're using FTP (file downloading) or Bittorrent, is absolutely miniscule to the general amount of internet traffic you probably generate. This creates a terrific advantage to those using Steganographic Technologies. That is why I think people, and vendors in particular, ought to be using obfsproxy and similar concepts.Lastly; for the truly paranoid/security conscious, you want to be thinking about a USP. A unique trick nobody else uses.For most people, having a consistent procedure and not doing dumb things like logging into IRC chats on clearnet is enough.