Solid Hardwood, Engineered and Laminate Flooring - Help !!!!

My father rented a machine from a flooring store that basically buffs the first layer of polyurethane and then you put another coat on and your floors are like new. Yeah right.

He had a few spots that totally needed to get sanded down to the wood and when he returned the machine the woman at the counter told him to stain the areas that were sanded to wood and then put the final layer of poly. She then told him if it doesn't look right to stain the whole floor.

Now if the first machine was just a buffer wouldn;t he be putting stain on top of poly and basically doing nothing but causing a real mess ??

Thanks

It will take a skilled eye here to know if there has been "too much" buffing for the amount of finish.

What kind of floor is it Oak? maple? is the finish light or dark give me a little more info and i might be able to give you some help.