It is a grey area....
Here are two examples that may play out when you provide an escalation clause.
1) Asking price is $170,000k You are aware of other offers. You offer $120K, but your escalation clause has a max of $160K, The seller has another offer of $150K but chooses to accept your offer because they take into account your escalation clause (They did this without countering your 120K because they knew how high you would bid), and they must provide proof of the other offer.
2) Asking price is $170,000K You are NOT aware of any other offers. You offer $120K, and provide an escalation clause with a max of $160K. The buyer DOES get to see this! The buy just rejects your offer and "knows" you are willing to go higher, they counter with 155K with the reason of "because they want to counter" .
So I would never use a escalation clause if you know the winner will always be someone that will always out bid you such as a potential owner occupant home buyer, or a more savvy investor (more experience with contractors and pricing)
Usually if you are bidding very similar to other offers, then the seller would usually ask for a "highest and best" offer. In this case escalation clause may have only worked against you. Just my opinion