I might be misreading the point of your post, but I’ve been lowballed before by a prospective buyer and my response has been to say “no” and choose never to entertain offers from that individual again.
It might be hurting myself (to a small extent) but I don’t see the necessity of negotiating with a person that has just insulted my intelligence. I don’t accept that as a tech trans lawyer and I wouldn’t accept it as an owner.
25% off the asking (whether that’s its true value) is usually not a “serious” offer. It’s a waste of everyone’s time from a negotiating perspective. You might be trying to have fun trying to score a deal, but unless the seller is in serious trouble, why would they even start a negotation?
Why would a buyer agent even take you on if he/she thinks you’re a waste of time?