Many groomers are using the diamond dremel bands rather than sandpaper ones these days and yet hardly anyone thinks about them needing to be cleaned, but they really do need it!
Nail dust, skin cells from yucky nails, dirt and even blood is present on those bands after use and it will build up over time to make the surface smooth not rough and it will make the bit appear to be dull when in fact all it needs is all that gunk cleaned off.
It can be done easily if you do it regularly, like daily or weekly at best, but if you do what I did and forget it can be a bit more tricky.
If you are doing it daily or weekly, you can simply use a stiff toothbrush and soapy water. I run the dremel while soaping it up with the brush and then rinse with hot water. Its easy. You can also take a brass brush and simply brush the bit clean.
If its incredibly "gross" it is going to take more than just a brush and soapy water. For those I suggest soaking in peroxide. I use a brush every half hour or so during the workday to loosen the debris then allow it to soak overnight. In the morning use a stiff brush to remove the remaining debris with ease.
The bit shown below has been in use since September and was so grungy I thought it had grooves in it and it was NOT working at all. NOW?? It sparkles!!! The grooves were there but they were in the grime and it wasn't working because the grit was covered by the debris.
I just got a tidbot of news from Jeff Andrews (NorthernTails Sharpening) that if you have an ultrasonic cleaner you can drop the bits in there and they come out great! I don't have one but its good to know for those of you who have one!