The last 4 singers I've played in bands with were found as follows:
Craigslist - male, great chops, diva attitude. Yes, I meant DIVA as in, b!tchy, whiny and overall just immature. Great singer with the mentality of a HS choir singer.
Craigslist - male, great chops, flakier than a dandruff infomerical. The dude had an excuse FOR EVERYTHING regarding not learning words, missing practice, etc. He actually BAILED a gig after 2 sets with 1 set to go! Another great singer, but overall a headcase.
Longtime friend - female, classically trained, super talented, good looking. Retired, due to motherhood.
Craigslist - male, singer and plays keys\gtr. Not the best singer but great guy, talented keyboard player. Pretty good guitar player. ZERO attitude or issues. My current gig.
BTW - Understand it took A LOT of auditions to find the first 2 I listed and even they ultimately turned out to be problematic.
It's such a crapshoot finding musicians via cold calling off Craigslist or wherever. Best thing to do is network with the local bands in your area and find people. I've found more friends of friends that play music that way.