Lately I've seen things in people's sandboxes: reserved model lists. I just want to say good for you, but if they're not on the list I'm sorry to say you have no reason to complain if someone takes them. They also don't have any need to ask to use them first. So, if it's not on the list and someone decides to use the model, well, you'll have to search for another one. Since, again, you have no say in the matter because they're not using your reserved slots on the list. I get wanting to use a model badly and then seeing it in use. Then not being able to use them upsets you, but again you can't get upset over it. Also telling people you'd like to use the model is also a good thing to do. This could give headway to no one using the model.
Plesse refer to the blog that Jaye made, before getting on someone about a model.
Rude headers for these lists will not be tolerated. Please refrain from putting things like 'don't be an ass' 'don't steal my models unless you want to fight.' It's not a polite thing and might incite something from another user. So please change the header if its like this.