To be honest, I think you can tell the difference between someone who uses terms of affection inappropriately out of habit, and someone who thinks he's a big ol' charmer chatting you up and wasting your time.
I do hate being called "darlin" and "hun" and will probably not respond to an email that doesn't contain my actual name anywhere, simply cos it's more likely to be a copy & paste job from a TW/worse. But if it's during an actual booking it would be fine, obviously! That's very rare though because I think I inspire more of a "yes miss" attitude than a "hi babe" one in person.
Similarly, it's rare for me to have someone be ovebearing on the phone to me but it's easy to deal with them: Just wait til they start asking how you are, what you're up to etc, and then yeah, they'll burst out laughing and hang up (if you don't do the same first) because they're just some kid messing about with their mates.
A genuine client is even easier to recognise, since all he wants to do is make a simple appointment, so you can always focus on that, too.