sorry if i put J at risk, i thought bart did the same thing! ~"When an inner situation is not made conscious, it appears outside as fate." Karl Jung~
ET is not a commercial site - membership is free, there is no income. And it would be fairly easy to prove that the context is one of 'social commentary' in the broadest sense. As a non-lawyer, I think your posting of copyrighted material with acknowledgement, or with link to the copyright owner's original publication, is acceptable, though lazy ;-).
I have occasionally posted copyrighted photos from Finnish papers myself, where I could find no alternative - assuming, as you do, that it is unlikely that the copyright owner would ever find such a use. And if they did, would they bother to pursue such use?
But the fact remains - are you adding anything to the copyright by simply reproducing them i.e. within the context of political, social and business commentary in which they are presented)? It is a tough one.
more info You can't be me, I'm taken