I've come across basically three types of movie poster dealers on Ebay. I've described them below:
1) The very trusted, razor-sharp professionals. Usually you get good prices, good service and fast and safe shipping. When there is a problem, they almost act happy to resolve it. These are few and far between but there are a handful of these on Ebay. I can think of 5 or so without much thought.
2) The haphazard, careless and distant dealers. Usually you can expect your purchase to never go 100% right. Even when you inform them of a problem, they act as if it were expected and remain detached from the situation. Sometimes you will get a problem resolved, sometimes not, but the overall feeling is that they are used to these types of complaints and are just "playing the odds". Even negative feedback doesn't seem to phase them much, if at all.
3) The semi-professional, but sometimes sloppy and VERY fickle types. These dealers seem to communicate with you almost using what appears to be gibberish nonsense. It is possible to get good service from these types but more than likely they will "forget" about a flaw, etc. at some point down the road. With these dealers, learning about their mistakes becomes a personal issue and they will "teach you for teachin' them". I've dealt with at least 2 of these dealers before and informing them of their mistakes usually results in being blocked, yes, even when they made the mistakes or non-disclosures.