sarek2k and Zetr0 - your application of copyright law and legality is flawed since you aren't the copyright holders. All you're saying is what you'd like to see in a hypothetical situation where you do hold the copyright. This isn't very helpful!
How could we possibly please all theoretical copyright holders in that case? One such person suggested that we include game downloads - "otherwise your occupation is the lowliest of the low documentation of history". Another wanted all the data for his own database and in his confusion called a non-HOL team member a thief and suggested that he had no decency.
Copyright is never as simple as is usually presented. As is often suggested its purpose is not simply to protect creative works but also to foster creativity. It can be more succinctly phrased as "the letter versus the spirit of the law". I'm fully convinced that we're adhering to the spirit of the law and the letter of the law is an area for the legal profession.
If you say that we have no right to watermark site content then logically we should be removing all screenshots and scans from the site. I can't see how you'd be for one and not the other in saying that we don't have the right to watermark. A poll should therefore be whether the HOL should be a textual site or have content.
It has been suggested that with watermarks in screenshots we're claiming ownership of the graphics. We're not. What we are protecting is the particular selection and arrangement of screenshots. That is, we're protecting the creative and intellectual work in selecting particular screenshots from the multitude of possible screenshots and also in the arrangement and ordering of them on the page. Furthermore, the watermarks are protecting the hard work that goes into putting together the database. In the EU databases may be protected in a dual manner by the law; firstly by copyright in the selection and arrangement of contents and secondly through the Database Right, which protects the hard work involved. For scans it's the hard work that is being protected.
A poll on using watermarks would have a predictable result in that most of us don't want them including the HOL team. Unfortunately it's necessary.