However, after 20+ years in the business, I don't ask for them much anymore, and don't really need to provide them in order to validate my experience with new clients.I don't think it is an unreasonable ask. 

If they are unreasonable and he just likes whining because he has nothing better to do, you can learn to ignore him or get rid of him.

But we also dont want to be unreasonable.  

I don't think it's unreasonable to have a price escalation clause if they can prove the difference as I have with my clients.

On top of this I would ask around on local message boards and/or other investors who have used them.50% on a small handyman type of job isn't unreasonable, but 50% on a large job should be pause for due diligence, not that I wouldn't do it depending on my trust and experience with the individual but definitely a cause for due diligence.As has been said before, for every shady contractor, their is usually an equal number of shady customers.

What effective ways have you used to educate the seller and listing agent that this low of expenses is unreasonable?

Bart Hedgcock I think what you're talking about isn't unreasonable and underscores the need to stress-test deals.

Then we could have asked for closing costs paid by the seller, lower price, or something else up front to ease our worried minds.After talking to other folks we realized that we had asked for "unreasonable" repairs. 

I need to take care of some plumbing issue  - the  quote my PM company gave is too unreasonable.

10.8% cap rate does not immediately strike me as unreasonable without knowing area, comps, building condition, etc.