There are a lot of guides to help you figure out whether a recruiter is serious or not. A recent thing that happened to me was that a recruitment agency refused

There are a lot of guides to help you figure out whether a recruiter is serious or not. A recent thing that happened to me was that a recruitment agency refused to let me have a chat with their client before I provided some references. It seemed weird and I really didn't want to waste my references not having even just a verbal confirmation that they were interested in hiring me. I really thought they were asking in good faith. It turns out that you should NEVER disclose your references with a recruiter before an offer is on the table, in writing. This is a very common technique and it usually means they are no longer interested in hiring you but they would gladly use your references as potential candidates or future leads to get more business. Very shady ;) TL;DR: do a lot of Googling of the kind "how to tell if a recruiter is bad".