Don't worry about insulting the seller.
First, determine the real value of the property. Second, if you've been pre-approved or pre-qualified, take that number. Third, determine how much you can comfortably afford to spend, which may well be less than your pre-approved/pre-qualified amount.
Take the lowest of those three numbers (value, pre-qualification amount, affordability amount). That's the most--the MOST--you should spend for the property.
Notice we haven't even discussed the listed price of the house? That's because it has nothing to do with the house's value, what you're qualified for, or what you can comfortably spend.
Now you can look at the listing price. Take the listing price and the number you came up with above as the most you can spend. Take the lower of those two numbers. That's your new maximum limit. If the owner's asking for less than the value, less than you're pre-qualified for, and less than you're comfortable spending, then you lower your offer to the listing price.
But never, ever, raise your offer if your own low number (value, pre-qualification, comfort level) is below the listing price.
And these calculations apply whether you're in Purvis, Mississippi or San Francisco.
Do not worry about insulting a seller. Worry about value and your ability to afford the property.