I'm flying with my family overseas next year and I'm interested in flying first class (usually 120k+miles). I don't even have a mileage plus account with United and the awards will be for United flights. I have two "friends" at the moment who will be making the bookings for me using their miles.

Question: Obviously the airline discourages the purchase of miles (didn't say I'm buying). I've heard of people getting caught doing this. How does the airline even come to the decision to follow up or flag an award ticket as a violation of their mileage program policy on the bartering/selling of mileS?

The obvious thing would be passenger names and the account holder's names being completely different. I can always say they're my friends (very generous ones too). It's my word versus theirs. Besides the obvious, what other factors would United consider or look into?