I've explored this painting vinyl issue on other sites, had a discussion with a friend and I also just completed the laborious task of ridding the MH of a 20 year accumulation of cigarette smoke and cooking film. To begin:
On one site a person primered and painted vinyl walls of a manufactured home he'd bought second hand. The primer and paint promptly peeled off in sheets.
As for my discussion, my friend and his wife are very clean people, I've stayed at their Alaskan home and his wife is a stellar housekeeper. Yet he was surprised to find an oily film on the top of a mounted sheeps head located 30 feet from the kitchen stove. Who would've thought that cooking grease would carry so far.
I just spent days cleaning the walls and ceiling of my newly purchased motorhome of what I thought was cigarette smoke film using TSP. However, the film was much worse in the kitchen area, which was filthy. The hood over the range was so sticky I completely removed it along with the grill around the microwave to clean them. I first attacked the area under the stove burners with a putty knife, it was that bad.
As a result of my research, my friends experience, my experience, and the experiences posted by the other board members I've decided what's paramount to painting over vinyl with a water-based paint is a thorough prep job and cleaning followed by the use of high quality primer and paint.
Steve