I believe CCC got a bit higher than 55% accuracy but I cannot recall the exact figure. Needless to say it was better than random chance. Tor is more resistant to this sort of attack than most other solutions are, for example many VPNs have had their traffic fingerprinted with accuracy that approaches 100%. However the accuracy of fingerprinting attacks against Tor has continued to rise. Recently there was some research of the effect of hidden markov models being used by traffic classifiers to aid in their ability to fingerprint sites, I have not yet read this yet but I am certain that using this technique will significantly increase the accuracy of fingerprinting Tor traffic. Pretty much if you have a malicious entry guard you are in a bad situation. If the person who owns your entry guard is a weak attacker with only the ability to see a small percentage of the Tor network, then Tor can still save the day even when you have bad entry guards. But as the attacker starts to be just a little bit more powerful the threat posed to you gets quite high depending on the exact circumstances. On the other hand though, if you have only good entry guards and none are owned by an attacker, you are entirely protected from purely active attacks. So a lot of your anonymity does depend on having good entry guards, but for clients it isn't a sure fire you are fucked even if you have a bad entry guard. Unfortunately hidden services are completely fucked if they have a single entry guard operated by one of their attackers. The scary this is that hidden services have some easily implemented attacks against them for detecting who actually owns their entry guards; the situation is a little bit less bad for clients but there are still some sophisticated and nasty attacks for tracing clients up to their entry guards.