Quick answer: not very well. I've sold 1200+ mints, bought close to 30 rares, all for trade price, right under their noses. Also done trades involving probably 500m total of junk. They can't track anything
TBH, its probably easier for them to track buyers than sellers. Ive rwt'd a few hundred mill with only one 10-day temp ban for powerleveling -.- which i wasnt even doing.
Yeah and they really have a 'People doing strange things' detection system. Think before you post, they'd have to be watching the accounts in the first place to catch them doing 'strange things' which raises the question how and why were they watching the accounts.
The only way you get caught RWT'ing is when you deal with businesses that have their IP or accounts flagged by Jagex.