I think he meant in the actual socket, not the chip to heatsink interface.
What kind of thermal compound? Arctic Silver and other metal containing ones would not be good. Ceramic, and Silicone based ones would be fairly safe in there.
If it were me I would go out and get new soft toothbrush and douse it in alcohol, clean the bristles and repeat until satisfied. Goal here would be to get the tips of the pins clean and no particles closing any gaps between them.