There are so many people in the world who are bad at their jobs, including, but not limited to, the people who hire people. Good recruiters are communicative, professional, prompt, and transparent. They introduce applicants to the position in a way that reflects well on the company as a whole. A good recruitment experience can even make difference for an applicant split between competing offers!
On the other hand, some recruiters are just plain incompetent, and others are very obviously scammers. It's relatively easy to tell when a recruiter is scamming you. Typically, they'll use extremely unprofessional language right off the bat. Either that or they will be extremely unspecific about the whole operation. No fantastic job has ever come from a recruiter messaging you on LinkedIn, "Hello. When can you interview." Usually, it's best to ignore these tricksters, but sometimes it is even more fun to mess with them.