Do not eat the melange! Other things besides fat have likely accumulated inside of your meaty petri dish. Meat juices and bits get putrid quickly, so unless it's collected over the course of one day maximum, there's a good chance some unsavory bacteria has been introduced in addition to the rancid oils.

Rancid fats are almost as bad for you as trans fats, which are awful. Fats can be rancid without smelling spoiled, and generally most fats turn rancid when stored at room temperature and exposed to oxygen. Put these things together, and my nonscientific analysis suggests that collecting and using the fats from your grill might not be a good idea.

I usually collect the fat rendered from frying bacon, though I keep the temp down so that it doesn't burn or smoke, which I believe breaks down the fat in undesirable ways. It is a particularly good fat for cooking potatoes and cabbage. But I don't think I would collect the fats from the grill, as I would be worried that they have been modified i some bad way.

Pop your grease in the fridge AS you collect it. Perhaps labeling it would be a good idea, too.

Not to mention the runoff on a foreman grill will also include cooked-out blood, water, and other things that when matched with the caloric value of fats could lead to all sorts of nasty.

Why use a george forman?

I cook my bacon in the am in a frying pan, once the bacon is cooked enough I scramble eggs in the grease... I dont need butter etc and by the time the scrambling is done I have no grease left.

I do this with all foods, last night I cooked sausages and the left over juice I poured over my steamed veggies for flavour..