I wonder ...how hard is it to check ISP locations? Can IT experts easily flag Brooklyn and Patterson pro-JW posters?
I presume you mean IP-based location data to track down an individual user.
There's a reason FBI confiscates a user's computer when they arrest them: they had to establish probable cause by getting such data from ISP (internet service providers, the folks who provide your internet connection), and can check logs of activity that's recorded on the computer.
Most ISPs are all too willing to comply with law enforcement officers (LEO), since harboring hackers exposes them to liability for the hacker's activities, using THEIR network. Most don't require a warrant, if the request comes from a legit agency (but to be safe from a legal standpoint, the FBI DOES get a warrant from a judge, showing probable cause, based on whatever evidence they have). The victims of hacking attempts (eg WTBTS) are ALSO quite willing to cooperate with LEOs, providing logs of the traffic from their side. Cross-checking data is used to find matches, and from there, they trace back to individual users via their ISP/IP.
BTW, they also can cross-check discussions in open and closed forums, further strengthening the case, i.e. someone talks about their involvement here, and the times/IP's match, those words can come back to haunt some. Just ask the Anon guys who got busted (Sabu, etc), and have spent $100's of thousands for legal defense fees.
Having followed internet security for a few decades as an interested user (eg Security Now! podcast with Steve Gibson, as well as a few internet law podcasts), people who use anonymizers (eg TOR, etc) are in for a rude awakening if they think they are not traceable.
The biggest mistake Anon EVER made was going after FBI, CIA, NSA, Gov't contractors (HBGary), local and State LEOs, even Senate/Congressional servers, etc, a few years ago. They wanted attention, and they certainly got it.
Anon can try to fix their image, but that's the problem with mob rule: anyone within the mob can do something in the midst of a riot, and the entire crowd takes the blame for the actions of some.