You shouldn't waste any more time on spammers by spending it trying to vet your followers. They got to decide they wanted to follow you, but you're in control of the most precious thing we have: our time. Don't give then even 10 seconds that it takes to try and decide their worth. They don't deserve that power over you.

I've never looked at any person's Twitter account and judged them by how many likely spam bots they have. I assume spam bots follow people all the time and I don't hold it against them for becoming victims.