that's fine if the people are reputable. That is not often the case. As with any point of sale, there are honest people making an honest living, and then there are rip off artists screwing you over.
buyer beware. everyone knows that. if you don't you have no business looking to buy anything... if you get screwed because you were uninformed you have no one to blame but yourself.
i never trust what a seller tells me. i'll look it over and come to my own conclusions. i'll ask a friend to come with me for a second set of eyes.
when i was buying my mustang last year i asked a couple ford buddies who are very knowledgeable in those cars a million questions because i'm not up on the finer things and problem areas on them. they gave me a ton of info.. i had an entire check list on my phone for things to look at and look for.
its up tot he buyer to know what he is buying. its his job to protect himself.
Do the research. It'll help you make a better deal, get a better vehicle, and assist you in steering clear of bad cars and bad people.