Yup. "Filtration lines". I also charge extra to hand scrub the edges and under doorways.

I usually point them out if they are bad and explain that it will be an extra $10 to $20 per room if they want me to work hard on them. I use the vacaway Spot-n-boost Green, which works pretty well along with a long narrow grout brush from Home Depot.

If there are just a few moderate filtration lines for the whole job, I just scrub without saying anything.

I once cleaned a house that had been shut up and unoccupied for four years with the heat on! Filtration lines like crazy! They were 1 inch wide with occaisonal long fingers coming out into the room. I was brand new in the business and did them for free!!! It took five hours to do three rooms and a hall. If I could do that job over, I would clearly spell out an extra $20 for each space and pass on the job if I didn't get it.

I have yet to find any single product or process that I can count on being 100% effective every time. Cyclone sometimes. My steam vapor machine sometimes. Maybe both. I will first do a limited area, then ask the customer to come and have a look. I tell them my rate is a minimum of $1.50 per linear foot, but possibly more, if they want me to proceed. A few do; most don't.