If the listing does not mention how many lamp hours have been used or are remaining, assume the worst!  There is nothing worse than spending $500 on a sleek looking projector, setting it up, and finding out that you only have 10 hours of use before you need to replace the lamp.  Furthermore, be wary of listings that say the lamp has "0" hours on it.  The seller has most likely reset the lamp counter illegally, so what may look like a brand new lamp, might actually be a lamp that is on its last legs!
            Sometimes the seller has no way of figuring out the lamp hours, depending on the brand and model of the projector.  If this is the case, the best way to weed out the honest sellers from the bad ones is by looking at other projectors they have sold in the past and seeing if their customers were satisfied.

          If the image is not described in the listing, assume the worst!  If there is dust on the LCD panels, the image will be fuzzy and unenjoyable to watch.  Sometimes the LCD panels are misalligned, which is a huge problem and makes it so the the colors are off and out of focus.  Both of these problems cost hundreds of dollars to fix.  Make sure the seller describes the image as "perfect", "beautiful", "flawless", and/or "stunning".  That way, if you get the projector and the image has defects, you can contact the seller and refer to the listing and say that the product was not as described.

            Projectors and the lamps they house are very fragile and delicate.  Make sure your seller has specified how he or she will ship it to you.  Make sure that shipping is insured as well.  Unless the projector is packaged with the utmost care, chances are pretty good that the lamp will break on its way to your house!

             If the seller's return policy is just "No DOA Guarentee", that means nothing at all.  What it means is that when in shipment, if the $300 lamp breaks, you will have no way of getting any of your money back, because technically the projector will not be "Dead on Arrival".  It will power on, but because the lamp is broken, no image will be displayed until you shell over $300 for a new lamp!  Make sure the seller guarentees to protect you for at least three days after you receive the projector.  These projectors are expensive and are made to last, so if it survives the shipping, chances are good you are all set.  Protection for the first few days after you get the projector are what really matter.