In past courses I have taught, when we have discussed scope and specification, I may have asked students to provide an "unenforceable" phrase, and there are PLENTY!

• To the satisfaction of the owner - how do you measure that?!?
• Same with customer satisfaction
• How built to "industry standard?" WHO knows what industry standard even is, right? According to whom? Who knows?!?
• Sufficient pitch, pits and dents not allowed, the list goes on and on - how do you measure these?!?

So this question is different and ties to our construction law course concepts:

Feel free to supplement with your own research, and if you do so, please provide the link.

Your requirement is as follows: please select a phrase or circumstance, and discuss how it may make a contract unenforceable.

Please provide at least one reference (required) citing per APA Guidelines.