White maggots in bin?

Are maggots in the compost a good or bad thing?

I've never considered them a bad thing in compost heaps, they are there because something in the heap attracted the mother to lay her eggs there.

Since fly larvae are one of natures decomposers there is probably something in the heap that isn't decaying as fast as it should, but that also isn't really a problem, with the troops all working together, you will end up with good compost.
My compost heaps are full of beetles, larvae of several different species, lizards come by to feast on many of these insects, so they are helping my compost decay and feeding our lizard population.

Redhawk

I have a ton of flies & gnats that swarm my compost heap (especially since it provides warmth since we're getting cooler weather). I assume it's due to the manure in the pile, along with the daily dosage of urine & kitchen scraps (which I usually try to bury under the top layer of the heap). I haven't seen actual larvae yet, but I assume/hope they're in there at least helping break it all down.

Outside, not so much. If your bin is inside it's probably more of a nuisance than anything. If it's outside, I wouldn't worry about it too much. Just keep rotating the pile and ensure it stays moist.