Isn’t geting muddy and wet half the fun of mountain biking?
Ask any kid.
No, it’s not. I don’t like mud. I put up with it, but I don’t actually like it. I’d rather get thrills by going fast than slithering about at 5mph.
Re trail centres – Cwmcarn is totally rideable in any weather. Well – Twrch at least. There is a string of about five puddles at the beginning though. Cafall is still perfectly rideable too. There are some muddy sections but not enough to be a problem.
For mud-free areas, I’d say look at somewhere like Moab.
FWIW I did four sodden rides on the trot this week around Cardiff, and whilst very wet and muddy it occurred to me that there is very little clag that affects riding. There are a few trails like that but they are easily avoided. It’s a pretty good area for a wet ride.