Most DMs love communication && negotiations,
for this allows them to assume an active role in actual play.
Your referee will assume the persona proper to the creature your party is dealing with -- be it shy and hostile,
stupid, greedy, helpful, misinformed, or whatever.
Intelligent monsters will always balance the offer versus the expectation.
A lone ogre is likely, even with his rather dim wit, to recognize that a strong party will kill him if he attacks or demands too much,
so a small bribe is better than a risky combat to get flesh to eat and pretty baubles to have.
On the other hand, weakness will be exploited by any basically hostile monster unless it seems certain that more can be gained by other action.
Be resigned to pay amounts in excess of the actual value received.
As a player, you must earn what you gain.
Negotiation usually gives you o chance to get on with the earning process, or live to come back and fight another day.
Always be wary and use your wits, look at all facets of the situation, and then use your best judgment accordingly.
In many cases a payment, bribe, toll, share or ransom fee will enable success or survival, and negotiation is a useful tool to the expert adventurer.