When facing lower rated opponents every third or forth opponent lets clock rund down after a bad move or even on move before mate insteat of resigning. Those players should be banned
I found that problem in rapid chess and among lower rated players but haven't seen it much since I got above 1300.
The behavior is a fair play violation and can be reported using the report button on a player's profile. It looks like an exclamation mark (!). Repeated violations gets the person assigned to a pool with other violators and also results in a five minute delay between matches.
When facing lower rated opponents every third or forth opponent lets clock rund down after a bad move or even on move before mate insteat of resigning. Those players should be banned