Years ago, I worked for a over-the-road refrigeration company. The manufacturing plant was having a lot of trouble with the paint sticking to the surfaces. Turns out that the electrical assemblers were using silicone on the connecters as part of the harness assembly. Then wiping there hands on a rag and then using the same rag to wipe off the dust and dirt that got on the metal surfaces.
Took a team about a month to get the connection between the harness assembly using silicone and the problem with the paint.