You say you have never linked them, but I think that linking those IDs is a current thing corporations and the spooks are doing, or will be a future Next Big Thing.
If a user signs up to many forums, or sites with comment systems, with different usernames, if they ever use the same email address then the users can be cross referenced (trivially, if the site publicly publishes those addresses). If the user adds IM details to a profile, they can be cross referenced (ever tried Googling an ICQ number? It can be very revealing). Many forums and sites ask for a location, and those could be used as an indicator of the same person, especially if they publish their date of birth too.
With those things though, it is clear when you are giving away your own privacy. I feel there is other stuff that could be used to cross reference different users on line though. I think though that in the future (or now, and we^W I don't know about it), The Man will use some kind of AI to cross reference different users on line, anonymous users on line, and people IRL. People tend to comment on the stuff that interests them, peoples' points of view tend not to change, no matter what they call themselves. People's spelling, grammar, or other language habits will be pretty consistent. The same person will probably phrase the same subject material in very similar ways, and at some point spotting that could be automated.
I do assume that web users are being profiled these days. The likes of security services or corporations could write parsers for web discussion systems, like phpBB, Slash, vBulletin, etc., and other discussion systems like usenet. Businesses like Facebook or Google make their money off data on their users, so with the right contacts or money you can get at their data (In-Q-Tel, the venture capital arm of the CIA, invested in Facebook, so I think it is safe to assume they have full access to the FB databases). If captchas are routinely broken by spammers, fully automated forum-parsing is not out of reach of the spooks or data-raping companies. Shit, if companies will pay people to astroturf their products, then they would pay people to sign up to forums and make a few posts so an account can be used by a bot to trawl the site, whilst still looking like a normal user.
So yeah, whilst consciously not linking identities is possible, I think there are things that those who would like to know about the different identities can do to spot various IDs. But we have counter measures, though I doubt they are perfect. We can find a random web user, and copy their identity for use on some sites. We can use the spell checker sometimes, and not other times. Perhaps change the language in the spell checker to be different to your native version, like en-AU instead of en-US, Canadian French (fr-CA?) instead of fr-FR. Hell, write a post, and run it forwards and backwards though translation software. In fact, here is this post Babelfished to Italian and back:
You say you have not never connected them, but task that one to connect that IDs is society of what of the current and the phantoms are making, or will be a great future following thing. If a customer company in on to many tribunes, or the places with the comment systems, with different names customer, if the customers never use the same email address then can be reported (banally, if to the public place public those addresses). If l' customer adds details IM to one profile, can be reported (Googling never tried a ICQ number? A lot can reveal). Many tribunes and places ask a position and those could be used like pointer of the same person, particularly if they publish theirs date of birth also With those things however, clearly when have been guaranteeing via yours own confidentiality. I think that us it is l' other roba that it could be used in order to report the different customers on the line however. Task however that in future (or now and we^W the don' the t it knows to this end), l' man will use a sure kind of TO in order reporting the different customers on the anonymous line, customers on the line and people IRL. People stretch to comment the roba that she interests to them, peoples' the points of view stretch not to change, any thing are called. People' l' ortografia of s, the grammar, or other habits of language will be enough constant. The same person probably will express the same material dell' argument in the senses much similar and to a sure spot of the point that could be automated. I suppose that the fotoricettore customers are profilandi currently. The similar ones of the services or the societies of emergency have been able to write the analyzers for the systems of fotoricettore argument, like phpBB, the cut, the vBulletin, etc and other systems of argument like the USENET. The commerce as Facebook or Google makes their money outside from the data on their customers, so as to with the contacts or the money of right you can obtain to their data (In-Q-Telephone, the arm of happens them of risk of the CIA, invested in Facebook, so as to I thinks or sure to presuppose that they have full load approached the data bases of FB). If the captchas they are ordinarily routes from the spammer, l' completely automated tribune-analysis is not outside hand of the phantoms or companies of giving-colza. The merda, if the companies paid to people to astroturf their products, therefore they would pay people in order to sign in on to the tribunes and in order making some starter shafts so as to a customer can be used from a bot for pesc to strascicoare the place, while still being similar to a normal customer. Thus yeah, while aware not to connect the identities it is possible, I think that there are things that those who it would want to know approximately several the different identities can make in order to blot the IDs. But we have against measures, although it doubts that they are perfect. We can find a customer of accidental fotoricettore and copy their identity for use on some places. We can use the corrector sometimes and not other times. Perhaps changes the language in the corrector for being different to your version born them, like en-AU rather than UNITED en-STATE, French Canadian (franc-CA) rather than franc-FRANC. L' hell, writes a starter shaft and ago to work translation software however behind and transmits. In fact, it is this Babelfished starter shaft to Italian and the posterior part here:
Apart from not making much sense, that does obscure many of my writing habits!