Can this kind of thing be avoided by having a 'nice' account, which one uses to visit politically correct subs, and a 'nasty' account which one uses to comment on TD / TIA / [whatever else people find offensive]? Or would your two accounts' origins from the same IP address be visible to mods or other compilers of blacklists?

They don't care.. if you have ANY post or ANY comment on TD you are banned on 2x... and a bunch of other subs, amiright?