I'm not going to run them all either. I don't think it's disrespectful in any way - given the level of the competition, for around twenty of these maps I can tell from the screenshots that I'm not going to vote for them. Whether it is because of bad lighting, lack of personality or plain design mistakes, I don't need to run them to see that.
I will still run a small number of them, namely the ones that I can see as potential winners. Kind of a pre-selection process. I certainly see how people (including me) would find it tedious to run them all.
I'd also like to point out that from the other side, i.e. as a participant, I'm not going to feel offended or disrespected if people don't actually open my map before voting. Although that doesn't mean I'm against anyone opening it