They don't like you building stuff in the woods, if that's you mean, but to date I've not had any problems just riding random paths I've found (with random clearing of branches from the path to make them ridable). Mind you I don't see many folk when I'm out, so it's not like I've seen people who would complain.
As for places to ride.....theres not much classic alpine singletrack in vaud (or at least I've not found it). But there is some good stuff to ride, Mt.Pèlerin has some cheaky stuff tucked away in the forest, although theres a fair few walkers there at the weekend.
Rochers de Naye is pretty ossum, especially if you start the climb from the lake, thus getting a full 1600m of descending from the top, we always do this at the beggining of the summer.... as a sort of right of passage to the summers alpine riding on the 6" full sussers.
Leysin (full suss) is also good as is the Moléson (hard tail), they both have some alpine singletrack, but I've yet to link up some good loops there.
In the Jura around the Col de Marchairuz, I'm just starting to link together some sweet stuff as we live near by. I've started exploring a fair bit with a map. It's hard work though to find good stuff, and you end up looping around a bit to get the best out of the area. But it's perfect hard tail territory, with the best stuff tending to traverse the ridge of the jura. It's good though, the ups are short and sharp a bit like the downs and they follow in quick sucession. Tiring at 1400m.
I'm happy to share what I know, if anybody wants to hook-up for some riding when the snow thaws.