Christiaan Briggs said:
A user is not always going to know what is going to offend them until they have looked at the content. By then it's too late.
Disabling image downloads (which I do all the time if I browse a site from work) enables the user to read the alt tag and/or filename in the context of the descriptive content in the article. With a site like Wikipedia we can enforce labeling standards to ensure that nobody gets a nasty surprise when they click "load". It really is the ideal solution. I've used it for years.