I run a private instance, but haven't had captcha or email verification on because, well, it's just me and one friend that I don't think even uses his account. I have applications on and don't approve anyone because it's a personal instance. So far, I've had 5 bots apply. I'll put their application text at the bottom of this post.
Names tended to follow (noun)(noun)## format. One actually only had one noun. But it seems like having applications on by itself makes a lot of them just not bother with you. Even better, the wording of the applications was... odd. They'd stick out like a sore thumb in a batch of real ones, I think.
"I’m eager to join the World [email protected] community to broaden my global perspective and participate in discussions about current affairs."
"I want to join the Lemmy.world community because I’m curious to connect with fellow users and engage in discussions about various topics."
"I yearn to depart from Reddit and embark on a transformative journey within this innovative social network by joining your instance."
"Joining the /kbin [email protected] community seems interesting as I can engage in discussions about the platform’s development and future enhancements."
"Driven by the ongoing events on Reddit, I’m eager to join this instance and find the satisfaction and pleasure that has eluded me elsewhere."
Luckily for you, they haven't learned to count to a thousand yet. The highest number I got was 566. The rest were 1-2 digits.