the worst recruiters are those that don't look closely at your profile/resume and or don't ask you what your salary requirements are and then you interview for

the worst recruiters are those that don't look closely at your profile/resume and or don't ask you what your salary requirements are and then you interview for a job where you do well technically (i.e pass leetcode tests and system design) but the hiring manager sees that the role he is hiring for isn't a fit for your experience, nothing worse than spending hours on interviews where a simple screening would have sufficed to rule me out. These recruiters all ways say something like "oh we are looking for people strong in engineering", but if you and a person who had experience in the role are competing, he would get the job over you 8/10 times, so in essense they are just shotgunning candidates. This is why these days i always insist on meeting the hiring manager before we proceed with the technical interview.