I will comment on this.
Yes, I used the term troll from my background many years ago writing about patent trolls, so maybe it irks people, but people who complain about one word in a much longer article are maybe... missing the point.
Anyway, as you will probably notice from the article, I am not "picking the first photos that is convenient", but being sent the banner images etc by event organisers to promote their events.
Yes, I can go back with a form for them to fill in and confirm they have copyright clearance etc., and doubtless they'll check, and confirm they have from photo agency X, and maybe I should also check that the photo agency has issued clearance, and that they themselves have validated that the photographer has verified they definetly took the photos... etc etc etc.
You can see that there has to be a point at which you accept that someone in the chain is being honest.
The issue isn't me nicking photos that are convenient, but accepting that a photo sent to me to use in an article/event listing has been cleared by the PR/marketing dept that is sending it to me.
The majority of problems come from small orgs who may seem to lack an awareness of copyright, so to protect myself, I am now taking the decision not to use their images unless I have built up trust in the sender.
However, even large orgs have been caught out - one example was the large theatre that paid for a license to use an image in a marketing poster, only for the stock agency to object to it being used on my website because the license (weirdly) only permitted use in their publications and no where else.
That's a large org trying to do the right thing, and I am trying to do the right thing, and still getting hammered by... well, yes, they're copyright trolls.