I've been led to beleive that a slight smell of fuel in the oil is normal, but the difference between normal and a problem would be hard to tell.
I beleive however if your fuel pump seal fails, then the first point of contact is going to be the Cam Follower. If the oil is being diluted in this area then your Follower will show signs of increased wear.
I know this one could be difficult, but a good sniff around the Fuel Pump Piston whilst its out may tell of any problems too.
Also heard conflicting views regarding the sump filling up with oil.
1) Due to being diluted it will burn off oil easier and faster
2) Oil level will rise due to sump filling with Fuel.