I mean the sticky adhesive stuff. Usually bright orange or blue.
I was very surprised to see the MB manual specifying a grease on the W124 pad backings, but I have always had good luck with the sticky stuff, so I have stuck with it (so to speak...).
If you can get the grease off, you may just want to give the adhesive stuff a try.
[Tip: The newer stuff with low VOCs is ruined if it freezes.]
Just for reference, I put on ATE pads about 1 month ago with new ATE rotors. No squeaks. I usually choose carbon fibre 'sport' pads, but I was not able to get them at the right time. These OEM type pads are working well enough, so I may just stick with them.
I did have occasional squealing before the brake job, but I did not own the car when the previous pads were installed. I also took in some slight excess play in one of the hubs when I repacked them.
If there is enough play, the ABS sensors can rub on the hub and damage the sensor. That may explain why you had problems here from before your bearings were replaced. They can also get dirty enough to foul (been there), since they are magnetic, and they collect rust particles.
1986 300E 5-Speed 240k mi.