-snip-
IMHO ACCTseller and AccountSller are very easy too differentiate on first sight.
impersonating an username works if they look similar on first sight. as ACCTseller has uppercases in front (which is unusual - means more people will remember it) they are easy to differentiate.
People usually only see one name when doing business with someone and not all names that look somewhat similar. Thus someone might vaguely remember AccountSeller or ACCSElller or ACCTsElleR or something along those lines to be trustworthy. Now someone with a very similar "sounding"/looking name comes along and might be considered trustworthy because they are confused with someone else.
Yes, you should check that when doing deals.
No, not everyone does so.
Yes, its perfectly fine for someone from DefaultTrust to add a warning. It should not stop anyone from doing business with said Account, but will make sure there is no confusion. I have traded with accounts that had a warning attached in the past and never had problems.
-snip-
Numbers and red letters don't mean anything, what matters is the content of the feedback itself. The source it comes from, the reason, and the backing.
. 
