This would not work for TOR hidden services, as your connection would come from a new address each time it accesses the site. There's no really easy way to link an individual user on a website to a physical machine using "normal" connection information, since TOR purposefully obfuscates it. To identify individual people you have to do things like use Firefox exploits to trick the user into revealing their non-TOR IP address (as the FBI did recently after taking down freedom hosting).
I've seen it mentioned before by the Police that they look for signs of someone habitually visiting a site. If a particular address is visited multiple times over a space of time, they can presume that it is someone who is seeking such material and will probably find more evidence on their hard drive to cement a prosecution. An IP address that visits once and never seen again would likely be ignored by the Police, especially if it is a site you wouldn't expect to find it on. But this applies to standard HTTP traffic, not sure how it'd apply to TOR.