I think the fact that the Borgata uses a different type of chip than the rest of A/C, plastic I think, that helps keep them a bit cleaner also.

In places like the Taj that has never had a rack change in the almost 20 years they are open there are still chips on the table from day one

Does any casino in A/C clean their chips? not that I'm aware of but it would be a good idea if for nothing else just for the appearance.
I doubt that germs are really much of an issue, someone with the flu could pick up a brand new chip and transfer those germs just as easily