I must preface this by stating, I rarely clean the front or rear elements of my lenses, as I feel this leads to scratches no matter how careful one might be. So, I have to keep them absolutely spotless or if something like a raindrop or other gets on, a very careful use of first, blowing with a special can of air for cleaning lenses, then eyeglass or optical cleaning pads used with extreme care.
I am very careful about changing lenses, doing so in a protected environment when possible and not allowing a rear element to be open to exposure for over a second or two. Maybe a bit compulsive, but the rear elements on my lenses look new even after many years. And the camera, again, only a second or two being open before either a body cap or lens is attached. Sometimes the venue will not allow this, but I like the clean optics and find it is rarely necessary to compromise the lens. (Photojournalists in critical areas, accept my apologies)
So, I was at an event with a couple hundred folks last night, honoring benefactors for a university. Photos were being taken by the "University photographer" who had a D3s with 24-70mm f/2.8 on it. On the carpeted floor was a 300mm f/2.8 Nikkor, w/monopod, lying on its side, NO REAR LENS CAP. It sat for about an hour this way as folks walked by, a foot or two away on the carpet. I will not comment on the techniques of the photographer as this is not the point, here. Also, the equipment was no doubt university property and not that of the "photographer."
I will place my camera on the floor of my car, wrapped in a blanket and some old newspaper, primarily so no one will recognize an expensive piece of equipment is present. I do not have a problem with allowing the camera to be exposed to elements during a shoot. But, when the equipment is not being used, I think it deserves to be cared for and respected.
So, the question is: Have you seen "photographers" treat equipment in a manner which is inconsistent with good photos?