my biggest pet peeve (and it isn't exclusive to cars, but since that's what we are talking about here) is the description of one thing, but a photo of another.
as mentioned earlier, pretty much every car ad shows "2014 Ford Edge XLT - $29,995 or $399/month", but then have the picture for the Limited model with the nicer wheels, HID lights, etc. that costs $37,995...there should be a law that if you are going to advertise a price on a specific item/model, the photo shown MUST be that trim/version...i am fine if you want to advertise the mid trim model and show how good of a price it has, but use the photo applicable, not the one for another version of it.