When I was single?
Last time I was single I was also childfree, 30-years-old and very fit and honed.
Mine were:
men with kids
married, or not separated as in not living with her for at least a year, and yes, i asked for and/or checked for tenancy agreements and documents (i worked as a paralegal and had access for free to all public records)
small dick
unfit - losers who'd rather do substances than work out
skinflints
addicted to games, football, cars, gambling, substances or anything that compromised them from being a normal person
guys with low standards of hygeine and cleanliness. i was 30. if a man is that age or older and can't look after himself to a decent standard, he can try his best to find someone who is okay with that. if i went into their home and it wasn't ship shape, i was gone.
chauvinists, who often claimed they were 'old-fasioned'. bye, fucker!
men who would not give oral sex
men who had no drive or passion, loafers, unemployed (rare in the US as there is not much in the way of welfare)
men who'd fuck anything because 'it's just sex'.
boy men whose male friends were first priority, again, in your 30s, grow up!
the usual - controllers, liars, abusive fuckwits, guilt trippers (it didn't work for my mother, it won't work for you, asshole), etc.