If I happen to hear that a team/coach plans to play (or not play) their starters more/less than usual, maybe I'll place a bet (assuming the line hasn't moved yet).
But if you really think you can predict how 2nd and 3rd stringers are going to play (especially the QBs), you're either:
1) Fooling yourself
2) The greatest handicapper in the world
there is money to be made...certain teams /coaches try harder to actually WIN these games, meanwhile other coaches will only show pieces of their playbooks...