First off, this is hardly a scam accusation.Can these be tagged red?
Everyone 'can' be given red trust.
If you ask whether defualt trust users will do that, most of them don't leave negative trust to sold accounts.
(it might be different when the account had green trust before being sold)
If the person goes from A+ english writing a few years back to F- english currently?
That's a strong indication, but can't be definite proof.
I think I know a few
I think everyone knows a few.
I also think I know the user you're talking about.
No, Bought accounts need not to be red tagged until they are in hands of a crook or are hacked one.
To be fair, you're hardly the one to listen to in this case, writing from a bought account.