Your best to find a good agent is to ask friend and family for suggestions on people they have worked with recently.
Your listing agent has little control over the number of showings your house gets beyond ensuring that it's priced appropriately for the condition and local market and that, of course, requires a seller's cooperation.
You certainly do not have to paint but I personally wouldn't trust an agent who didn't suggest some basic sprucing up of any house. That's a good way (in my opinion) to vet the people who actually care if your house sells from the ones who just want a sign with their name on it in your yard.
Good agents don't suggest you paint to be a pain in the *** or because of their personal feelings about your choices. They do it because it makes a difference in how buyers judge your house and the vibe they get from it. Most buyers have a hard time seeing the bones under a bunch of crazy colors. It's just reality.