No, retractable itself does not preclude grass.
Plenty of TB20s for example live on grass.
The "getting dirty" issue is a bit of a mixture.
If you get a RG plane filthy, you have a number of components to clean and perhaps re-lubricate afterwards, but it's no big deal because everything is out there, visible and accessible.
If you get a fixed gear plane filthy, there is likely to be a lot of mud/grass inside the cowlings where you can't see it, and it will build up.
The only solution is a plane with fixed gear and no cowlings, but they cost a lot in extra fuel. Even on a 100kt PA28, cowlings are worth about 7kt which is an awfully high % of engine power. This is what many flying schools have; cowlings get broken, the fuel doesn't matter so much.
However, regular operation on grass does translate into higher maintenance over time, probably more so if RG. But the whole plane gets more dirty anyway, and ages quicker. Also one has to taxi with a lot more power on grass - not so good with a cold engine.
Always go for a hard runway if you have a choice, especially for your home base.
There are planes with extra small wheels which I can't really see on grass unless it's very good. I am sure people do operate the PA46 on grass but I wouldn't like to.