I've painted a couple of "miniatures" that are nothing more than soft plastic monsters.
Here is the downside:
See that missing chunk on the arm? You can't see the paint missing from around the hands or the tiny splits in the shoulder, but they are there.
First the figure got tacky - very tacky - which might have been the primer (I can't recall if I primered it, probably). Then that dried and paint is starting to fleck off.
Oh well. It's a cool figure, even cooler painted, but it's clearly temporary as a figure. Oh well.