I'm not sure what you mean by being careful with c...

I'm not sure what you mean by being careful with cars and property. Are you saying that somehow they are going to obtain a bad reputation by driving up on a construction site in a car spotted with mud from the last construction site they were testing at? Hate to break it to you, buddy, but usually when you work testing soils and concrete, you end up covered in soils and concrete. And usually the contractors you work for are as well, so no one really cares.