to some extent ... yes.

Check if they're using a proper washmitt. They should always be clean. If you see grayed and soiled washmitts... ehehehehe... Worse, if they're using dirty rags instead of washmitts to wash your car.
Next, check what kind of towels they're using to wipe the car. Again they should be clean. Dirty towels... scratches.

If you plan to have your car undergo a 2 or 3 step -- watch first how the workers use the buffing machines. They should be slow and methodical. Pag mukhang nag flo-floorwax lang ng sahig (halos random, tapos nagmamadali), then go somewhere else.

As for the products used --- megs vs moms vs etc.... They should be your last concern. Kahit na sabihin nila na ultimate high quality waxes ang gamit nila, if they workmanship is crappy... bali wala din.

Hope this helps.