Hello all.  Here's my input into this issue: 
I think we have to consider outsiders who may visit Renderosity who may not have that acute appreciation for the human form when they are not prepared for it.  For example, I work in a company of more than 15,000 employees, which has strict rules about what can be displayed on a corporate computer.  In my company, you are actually in violation of employee rights if others see you viewing nudity because it is considered a form of sexual harassment.  It's right up there with making sexual remarks and unwelcome advances towards other employees.  Our company actually presents movies along with trained human resource personnel to all its employees about what is sexual harassment and what should be reported.  We go through this training every year.  Why?  Because it only takes one person to get so ticked off that they run to a lawyer and cry lawsuit for the sake of harassment.  So this is a counter measure.

Because of this, I am always concerned about anyone at my job that knows I have images at Renderosity.  Myself, I don't produce nude images, but I'm worried that people I know who visit the site will be shocked by some of the images if they were not expecting it, especially if they are people I know at my job.  I always have to tell those I know that if they visit this site to be mindful of who is around them and where they are because of the nudity.

Another crowd I am concerned for are those that may be viewing the Renderosity gallery while at home where their children or spouse may be around.  Some of the material I've seen here is simply not Disney material.  Granted there are many fascinating and admirable images.  Unfortunately, I've seen some that I would not want my 12 year to see me even pass over on the computer, it is just not appropriate when trying to set an example of places you don't want them to go to. 
I must admit, I am rather uneasy at times when I go through the Renderosity marketplace if others are around me.  I basically have to try and shop when no one is around.  Sounds silly?  Put yourself in the shoes of an outsider viewing someone passing over icons of nude models, some of which are in rather suggestive positions.  If they don’t know what site you are at or what your reason is for being there then you probably look like a pervert.  I say this because my wife had a few wrong impressions of my going over the gallery.  And I’m talking just by what is shown on the surface pages with icons.  For example, in just the last week, I submitted some images.  I typically go to the gallery right after a submission just to see my icon there and others around it.  On one of the days last week when I did that low and behold on one of the surrounding gallery pages was some guy sitting on a rock totally exposing his family jewels to anyone who could see the page icons.  I did not want to see that and was thankful no one I knew was with me at the time the page surfaced.
Maybe we should consider the level of standards other “well regarded” digital art galleries uphold.  I stress the term “well regarded” because its too easy for anyone to throw up a site and say they are about digital art and put some pretty distasteful images up.  Those kinds of sites we should distance ourselves from in the extreme.
And so in closing, I would like to say I think it is not only a good idea to appropriately mark what is behind the icon for the reasons mentioned above but also for the future growth and reputation of Renderosity.  I'd like for others to know Renderosity as a fantastic digital art place that others can visit without concerns such as those described above.