This sort of reminds me of when I used to be a bookie back in the day! Well I had around 30 "clients", mostly college students, who would call in and bet everyday. Of course, no one had a computer, much less internet back then, so being a bookie was easy money! But i had some players who I KNEW who they would take before they even called!!!
FOr instance, I had guys who would bet on the Dallas Cowboys EVERY WEEK no matter what spread that I gave them! SO I would usually make the line -3.5 or -4 if it should have been -2.5 or -3. Of course they didnt know any difference since there was no one else out there to take their bets. And I would usually tell them that I wanted to "balance" the action. The truth is that I DID NOT want to balance the action since most of my clients were winning at clips of like 35% or so.
I mean these guys would take ONLY favorites with lines over 10 points or so in College. Now we all know that you will go broke FAST when you take the big favorites!!
But I would adjust the line on ANY favorite that they asked for in my favor and of course they would still bet it. Every now and then someone would take the other way, but only maybe 5% of the time.
Likewise, when i call into a book today to place a bet, I usually ask the book what is the line on the MNF INdianapolis line. It would appear that I will take INDY, when I really want Minnesota. Sometimes it is best to switch up your call in routine!