These quetches usually work in prisons, guarding prisioners. They have a nurse outfit and carry a baton. They usually can easily be tricked by Twinsen to escape his cell.
It's never stated straight whether they are clones or collaborationists, though their relative wordiness, snobbish attitude and the fact that they never use telepods, calling upon the clones with an alarm button instead, all point to the latter.
To escape the Citadel, Twinsen has to put on a nurse outfit to pass as one of them.