Customer pre vacuuming

I always ask the customer if they want me to per-vacuum there carpet, they ask if that cost more and I tell the price, some have me do it and some say they will do it there self. 9 times out of 10 when they vacuumed it , you move the couch or some other thing like it, you find all this junk under it. You are half way done the room and the customer ran off, do you go look for the customer, vac it yourself with there’s, go get yours from the van, pick up the big things and keep cleaning, or do you always vac yourself so this dose not happen?