Admins should implement a Geo-IP script to bring location flags automatically upon each signin. SO they will sort of follow the user. If he is posting from KSA and then he goes on a visit to Kuwait and logs in, his location flag will automaticaly change to Kuwait. Such database can be had for free and writting script isnt that difficult. Also on profile page there should be a display of last ten login locations so the clever ones coming through public proxies can be busted.
The HTTP X-Forward-For header provides the true destination of request and invalidates any masking by middle proxy or atleast makes it difficult. This would made evasion by proxy much more difficult.
Thirdly each signin attempt should be logged and checked against a database of public proxies. Such database can be had for free with regular updates from many sources. All logins attempts through public proxy should be flagged in the database for analysis of possible false flag members. Therefore, a rational analysis.
Fourthly a machine tracking cookie of random value created upon first visit with 365 days validity and signin neutral. It will provide a very valuable input on how many users signin from same physical machine / NT user account.
Member-X signin IP matches Member-Y
AND Their signin/signout time corresponds with each other = Possible troll with multiple ID's
Member-X signin in machine matches Member-Y
BUTdifferent signin locations logged = troll hiding behind public proxy / VPN / anoynomising services.
Member-X signin IP does not match Member-Y
BUT signin/signout times sync with each other = troll hiding behind public proxy / VPN / anoynomising services with selective cookie filtering.
Above are few examples of logical analysis however much useful trends can be captured to keep this forum sane and troll free.
This is a defence releated forums and we have to think like an intelligence officer
One source for Geo-IP database is
Downloads | IP-to-Country.com
and there are many free / paid others.