Can't answer that question...BUT...I usually test the waters with a little tap. You know... a gentle side tap on the hip while she's on top. Soft enough so it doesn't appear to be a slap... but hard enough to maybe elicit a response. Sit back and listen for a change in tone from her moans. If her reaction is a positive one.... bring it up in conversation after. If there was no noticeable reaction.. then most likely she isn't going to like spankings.
Anyway.... I'm more of a squeezer than a spanker... so i could care less.