I print on glass w/ hairspray.

Over time, the hairspray can build up considerably.

I've noticed that "heavy" ABS prints w/ little infill, can become, er, quite attached to the glass/hairspray.

When things start to reach that point, I take the glass off and give it a good washing in the sink..., carefully.

FWIW, I also tend to keep my bed temps for ABS quite high relative to the original MF settings. Depending on the print, I may leave it at 110C for the whole print, or slowly bump it down to something like 102C.