What should I look for buying from Craigslist (New chairsofter, more questions)

Looking to pick up a my first gun for somewhat all around games and backyard pickup games. Looked at craigslist and found this. (Also, wow, that spelling, just wow)

I read that JG makes decent/good stuff, and the G36 is listed in the beginners guide.

But not knowing too much about airsoft guns, anything in particular I should look for when I go check it out? The seller painted it, but otherwise, its just what you see in the post.

So what should I ask, and what should I look out for? Thanks!