I have a shower pan that is over 20 years old. It is like a plastic material with a rough bottom. It never is clean. When I do get it as clean as I can it scums up again rather quickly. Is their a product I can spray on it like a paint or the like. Similar what some people do on an old cast iron or steel bathtub. I have seen a couple of bathtubs re painted and they look great. Thoughts?

Another option is to remove the bottom course of tile and remove the pan. Can this be done? What are the pitfalls?

3rd option - gut is all and start from scratch...?

You could try an epoxy paint or a fiberglass gelcoat. You would want some anti-slip particles added to mix. Critical issue is how flexible or better how inflexible is the plastic pan. If it flexes much at all with pressure,likely any coating will crack and come off

It's textured so you don't break your neck. They're a PITA to keep clean.

The house I recently bought has bathtub/shower combo units with texture like that. Mine is fiberglass and the texture is in the gelcoat. As mentioned above, it is a pain to clean, but I use a stiff short bristled brush and scrub. It helps, but it always looks dirty in the bathroom where the light is farther from the tub.

It can be done, but it would take removing more than just the bottom course to take it out in one piece and put a new one back. Finishes do not always stick to plastic.

Try foaming bathroom cleanser. Let it sit, then make sure you rinse it. The old-fashioned scrub brush works also. I've used one with Bon-Ami before. There's no easy answer. All modern fixtures have some type of texture.

You might research shower mats to hide the present floor, also wooden mats are available if they match your decor.

From my experience..they get dirtier faster than the texture.

Once the smooth gelcoat is damaged by scouring, there is nothing that will keep them clean.