I do not know much about Mammoth specifically but most resorts are similar. Be prepared to be treated like a second class citizen. Almost all resorts treat their employees like shit. Living in the dorms can be fun since most people are just there to have fun. However, try to get a room by yourself or find some place to rent if you can. I remember some people that lived in dorms had bad experiences. The dorms were most of the seasonal people lived were the worst. Like people would get shit faced and barf all over the room and bathroom as well as yelling and screaming at like 3 and 4 in the morning, people getting in fights, and a lot of shit getting stolen.
Also If you do not show up to work and go snowboarding they will flag your pass and a lot of times fire you so if you plan on doing this try to buy your own pass.
Some jobs at a resort can be great but most are really bad. I know some people that work at the resort that get to ride 7 days a week. They work at night for the resort and get to ride all day. So it all just depends on the job but a lot of the jobs are a shit show.
also sometimes if your nice to people in your department and other departments as long as there not dicks you can get a lot of favors like free food or better shifts that let you get out and ride more.