and its best to have a safe word, so things don't go out of control.  

There is nothing wrong with slapping or smacking a woman, if that's what you have mutually agreed to do.

Seriously. Unless we've met a number of times and I've given you very clear signs that I would want to participate, do not hit my face.

I have literally had people smack me in the face, HARD, as soon as I open the door. This generally isn't a fantasy that implies anything fun for us, and for the most part, we aren't going to be ok with it unless you explicitly ask.

Spanking? Start with a light tap and I promise you'll know where we want to go with it, lol

As long as you are just talking about enough to just make a pink mark.  Gals like to spank and be spanked, and I find that quite delightful as long as she does.  Light to medium pinching is another related practice.   Some gals like to go with a paddle, but that is hardcore BD/SM, not my bag.

But slapping, that is another level altogether.

I do have an experience with a gal whom I have known for a very long time.  She likes sex but never had an orgasm, so I asked her about that.  The answer I got was not quite what I was expecting, but she told me that as a result of a very disturbing childhood vis a vis sex, she could only get off if her face was slapped during sex, and she entreated me to help her by doing so.  I was pretty concerned and not at all feeling sexy doing this, but at her behest I started to slap her, enough to leave pretty noticeable red marks on her face, but she kept saying to smack her harder and harder, so I did. It took a couple of minutes that felt like ten times that but doggone it, she did get off from it and thanked me profusely for doing so.

We did this maybe 3-4 times over the course of a year, and thankfully she said she finally got the need out of her and we don't do it now.  She doesn't always come when we have sex, but she says she enjoys the closeness and the feeling more than the orgasm anyways, and I'm coming around to the same point of view.

Another upsetting practice is verbal abuse.  Now I don't mind if a gal wants to do dirty talk where she says stuff like "I'm a slut, fuck me hard.", etc., but recently a gal wanted me to say like things back to her, and I found that a buzz kill, especially with this gal since I hold her in very high esteem.

She was a little tipsy at the time.  (That's putting it mildly.), So in the future I hope we can have our session before we go out and wine and dine.

we just stumbled into on our first meeting. In mish she just slapped me across the face, quite a surprise, and told me to fuck her harder. I said, ok, but lay off the face slapping. Then we switched to k9 and yepp, she wanted her ass slapped. Ok, I can do that.  At the end of the session we discussed the aspect of her getting off on rough sex, so the ground rules were set for the future. It's all about communicating, hopefully before the activities begin,  and now whenever I want that type of session, I give her a call.  

But that most certainly does have an element of BDSM to it. If I were in your position, I'd search for ladies whose profiles include BDSM to some degree. I think those of us who like it are probably fairly rare.  

That said, don't go crazy with the smacking. A light slap here and there is cool with me personally, but I once had a guy slap me so hard that everything went white for a second. This morherfucker put his shoulder into it. Not cool.

My question was: should I even ask her about slapping on face.
The answer seems to be "No, unless if its a BDSM or S&M session", which I too find quite loathsome and doubt if that's something I will ever ask for.
Spanking seems okay to begin with a light pat, and then let her dictate.
Thanks every one