I do OWO as no matter what condoms I use I gag on them. Just the thought of anything rubbery in my mouth makes me gag, ever since I had a tube down my throat at the hospital and they forgot to sedate me and I was gaging and choking on the rubber tube. Urghh I am shuddering just thinking about it. I have a couple of clients that prefer OW and tbh I always try to put them off by saying I am busy as I know I wont be able to do it for more than a couple of seconds before I start gagging
Lord, that's horrible - I'm not surprised it's difficult.
I have a horror of choking, but it's having anything around my neck that bothers me (even things like T-shirts have to be lowish) and it took me a solid month to get used to doing it, but I don't even think about it now. I've coughed and choked when a punter with a long one has tried to shove my head down on it, but I would have done whether there was a condom there or not and I think most people would.
What I did find when I stopped was how much more relaxed and happy I felt, and how much more enthusiastic I was as a result; I also learnt a lot about using your lips and tongue and applying different pressures and techniques, because obviously the condom means you have to work harder

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I did get punters asking if I was going to stop doing anal and some other stuff too, which I thought was a bit odd but they maybe associated covered oral with only doing very vanilla stuff. Going back to the OP, I don't honestly think I'd have lasted a year if I was doing stuff I wasn't OK with just to try and get more business.