I dislike them because they are apparently a wormhole.
First, I'm old, and the images are TINY. So I am never sure I've found every submicroscopic car that might be lurking in them.
Second, even when I put on my superglasses and am sure I did it right, all I get is more captchas.
Third, even when I go back and take out every scrap of BBCode and every single image, it continues, which tells me that there is no, repeat no, discretion in the thing. Once flagged, there is no fix and no appeal, apparently.
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"I believe you find life such a problem because you think there are the good people and the bad people," said the man. "You're wrong, of course. There are, always and only, the bad people, but some of them are on opposite sides."
-- Terry Pratchett, Guards! Guards!