I think you are doing the Nanny thing a little too much.(I guess now I will be expelled and my post deleted).Let's all just smile and say sweet things and look out for the principle who has set the rules of "niceness".
So I would be allowed to say "smokin deal, great price, love that car " etc...,
could I say for example " fair price, typical car, average wear, seems about the right price, one sold for about that a few weeks ago on Ebay...etc"...
but never:... " hmm, not sure about the color combo, those wheels don't really match, that engine can be hard to keep in tune, seems strong money considering what the others have been selling for recently".