A lot of people ride them wet. My husband did a 24 hour ride in the rain that ruined his saddle. there's a big difference between 2 hours and 24 hours if you catch my drift.
A lot of people here in the NW USA (where it rains) have Brooks saddles. I have ridden mine in the rain with no problems at all; many many times.
If you ride extremely long distances and are in a rainy climate, you probably would be better off with an An-atomica