Hi there, and welcome.
A tricky one to answer, since I can't see the car, and what one person sees as a major blemish, somebody else would live with quite happily.
If you just want the car off your hands (quickly), and to have a clear conscience regarding probing questions - I'd be inclined to auction it (at a proper car auction house).
If you take a car to a dealer (or around many dealers), unless he has a customer already for your car - he won't make a high offer. You'll have wasted your time (and fuel) and gotten nowhere as a result.
Selling privately has its own probs - people not turning up, calls at all hours (not easy when you work shifts), test pilots & timewasters, telesales, etc.
At least at an auction, you may get a few dealers (and a private buyer or two) bidding against each other - you probably won't get less than a dealer would offer (you may get more), and you've saved a lot of effort.
Regarding tidying the car up - have you considered doing the work yourself? I have written articles in the "How to" section of the forum, and if you are relatively handy, you can do a fair bit to improve the car's appearance for not much dough (certainly less than a classified ad).
Hope some of this helps - p.s. if you are auctioning it - don't waste money servicing it - a dealer will do it anyway, and a private punter won't bid any more for it.