Quick cabinet painting questions
In my view, on the flat horizontal surfaces, like the tops of shelves, fixing rough paint is simply a matter of scraping/sanding it down, and applying a thinned coat of paint over it.
Thinning allows a paint to "self level" so much better. It both reduces the viscosity of the paint and increases the drying time so the paint has more time to flow faster into a flat smooth film.
If the problems are on a vertical surface, I'd do the same thing, but use either Floetrol (made by Flood) for latex paints or Penetrol (also by Flood) for oil based paints. These paint additives will thin the paint without lowering it's viscosity so that it has more time to dry, and therefore self level to a flat, smooth surface.
That is, I think you can do a decent job fixing any glitches yourself.