Similar logic applies to contact negotiations. Which sucks, because being fully diligent is can also set the "hard to work with" bit and kill the deal too.
It's likely that the best way to handle this is the simplest: renice the M&A conversation down to 19 or 20, beneath everything else you're doing; be legitimately annoying to work with, conveying the impression that you don't need the deal because it's the truth.
Very true. Of course if a party makes this mistake they can easily put the fear of god in the other party by changing their pattern of response.
If you tend to reply in a quick fashion and appear very eager and then all the sudden there is radio silence the other side will intuitively know something is wrong. (Ever have that happen with dating where the girl all the sudden doesn't respond as quickly and you know something is up..)
The mistake that most sellers make is assuming that someone's eagerness is locked in. That a party doesn't change their mind or doesn't have another circumstance come up that makes a sale unlikely at any price. (Similar to what the OP was saying.)
No deal is done until the fat lady sings.
The domain in the example I gave I recognized would have no other buyers essentially. So I advised to close the deal as quickly as possible even though a little money was left on the table. But many sellers simply won't take that advice they are gamblers.
Here's an example that is playing out right now.
Name offered for $6000. No other buyer for this name. If it doesn't sell it will probably never sell for 10 years.
First offer from buyer:
"Thank you for that. I could do $1200, but that is not really in his ballpark. If he changes his mind, please let me know. You are welcome to take that offer to him."
What he did right: Made offer and made it seem like that's pretty much the range he will pay. "If he changes his mind let me know" as if he is going away. So a seller would think he can probably get $2500 out of this type of guy maybe for this name. (Nobody ever makes the first offer the best offer.)
What he did wrong: No time frame to transaction. No sense on the sellers part that he could loose the deal. No sense that other names are even being considered (even though that's normally bs and can backfire).
Reply from seller:
(A short sales spiel showing why others would want the name) ending in "he might do $4000 but I have to clear that...".
Reply from buyer:
"Please ask him about how low he will go. I will see if I can get there."
What he did wrong: He essentially didn't barf at the $4000 for the name. He gave no kickback. So seller knows he can get that amount most likely. And maybe more.
Seller:
"Ok I will find out" (or something to that effect).
Buyer writes back quickly again:
"I am feeling pretty good about that. I think we can do it or very close to that."
Somewhat good: "I think we can do it or very close to that". That essentially says he will pay the price but he gave himself a little wiggle room.
Bad: He replied to quickly to the email showing he was very eager. Time and tempo are important.
Then he writes back again a minute later to say he is ok with the escrow company and will write back soon. So he completely telegraphed his intentions. Even though he hasn't really agreed to purchase.
By the way this was a lawyer as a buyer. And this is the same stuff that happens with 6 figure domain sales as well.
So the deal right now is going to happen at $4000. The seller is fine with that price and doesn't want to loose the deal for fear he will get nothing.
In this case the buyer overpaid if he handled it correctly he could have had this name for $1500 about.
And as mentioned multiply by 10 and the same stuff happens.