How grim is too grim?

I'm writing an adventure for a dark fantasy game and I like the background blurb I've done; a few paragraphs describing the location, it's history, and what the adventurers find when they arrive here. I've talked a lot about the bleakness of the place and even offered some hints on just how miserable, damp and grey the location is. This is for a miserable, horror-laden scenario that I hope will tax not only the strength but the sanity of the player characters.

Then I found myself editing a lot of the bleakness out; I read it back and part of me thought, 'How depressing - why would anyone want to play this?' It really was overbearingly miserable. I'm all for setting a scene, but not to the point where players walk out of the room crying after realising that their existence is pointless.

I've got to strike a balance between what makes an adventure atmospheric and what makes it enjoyable. Yes, it's a bleak horror story but there can be a side to it for people to find the experience fun, but I think I have to trust the GM of the game to invoke that atmosphere, or at least invoke a level of grimness that the gaming group enjoy. After all, that GM knows his group and the group know what kind of game they want to play in. I can't impose my play style on people I've never met. All I should do is present my story and adventure and let the GM do the rest.

In the end I've expressed the atmosphere in the intro and some of the background, and I'll no doubt use the words 'grey' and 'miserable' during writing, but I'll not enforce a type of game or a style of gaming that a group might not want to play in. That's not up to me.