Fair enough questions. I wouldn't say the discrepancy in taggings are "double-standards" so much as demonstration of a "case-by-case basis".
For me personally it depends on whether I believe the users in question have honest intentions or not. It would appear that the alt of HedgeFX was banned for PM spamming. As he no longer PM spams and has been a fairly honest member of the community thusfar IMO (and not even enrolled in a sig campaign), I think in this case forgiveness is warranted.
Not that its even up to me -- its totally the mods' call as to whether he should be banned or not.
As far as tagging members for ban evasion is concerned, I would only do this if its obvious to me that they are evading a ban, although the technical proof required by mods to perform the ban doesn't exist on-forum. Usually when I mention it in a trust rating, it is in conjunction with some other offense, and not the sole basis for a tag.