A smart woman knows to go down on the guy first. That way, you have some time to "recover" while you are going down on her.
Myself, if things are at that point and she's not initiating on her own, I usually say something like "Erhem... you'd be better off to do your thing first, trust me." along with a little nudge, nod, or look south. Usually you'll get a "Huh?" look, followed by the "ooOOhhh" look, then instant compliance, without anything else said. But, I make sure to do this the first or second time I sex a chick. The reason is, they'll be left with: "Wow! He was right! I'm going to remember that for next time!" And, that sets the standard right from the start.
However, some chicks are just shy to initiate like you mentioned, Amoka. In those cases, what I do is go about business without making any big deal of it. If I get through the whole thing without her reciprocating at some point, then I know that for next time. From then on, (or after 2 or three times to demonstrate that the prowess isn't a fluke, or her lack of receprocation is the norm) I don't go down on her anymore (Why bother?). If it turns out that she brings it up ("Why don't you go down on me? Do I smell funny?"), I'll explain to her: "Reciprocation is important to me. It demonstrates equal efforts and involvement. You scratch my back, I scratch yours: fair is fair. You, Missy, have yet to reciprocate, so I've reduced my efforts to equal yours."
Of course, you get the "but I don't do that" bvllsh!t sometimes. In which case, you've already set yourself up for the: "Well then, neither will I: it's not fair. Those chicks aren't worth staying with for any period time. I call it a huge red flag: it demonstrates that she's incompatable because she is selfish, sucks in the sack, and unrealistic.
I have a hard enough time staying with "spitters" just because of their unrealistic views. Be it that they spit because of the texture or the taste, it doesn't make ANY sense to get up (and fux up the flow and mood of the scene) and go to the bathroom (or wherever) to spit. Why would you keep a load in your mouth for LONGER? It doesn't make sense. Gulp it down, I'll hand you the water, and we can get back to the business at hand. As for the chicks that spit that sh!t on your stomach, they get handed the spuzz rag and told: "What the fux? Clean that sh!t up."
Handle it based on how important it is to you.