hudi,
I see manners and Middot as two sides of the same coin. Middot are internal and manners are external. If you worked on your middot, you should have good manners. For example, if you taught yourself patience, you won’t cut a line.
One would expect that a Yeshivish person, who we assume learns mussar and other ethical teachiings, to have internalized the ethics and act with manners. Therefore, I think that they are being judged more carefully, and maybe rightly so.