I gave a bid to a local CVS last year for an exterior building wash, sidewalk and dumpster pad cleaning, and gum removal.
I really wanted the job, so I bid it very competively, hoping to get a foot in the door.
After two weeks of hearing nothing, I phoned the store manager, and was told they had a lower bid, and went with that one.
A week or so later, I saw a guy washing with a cold water rig, no chems, and no surface cleaner. He didn't get the concrete real clean, and the gum spots were still partially there. And the dumpster are still looked like hell.
So my impression is that they were looking strictly at price, and not so much at really doing the job right.
Unless you really need the work, it may not be worth your time.