I just got challenged on programmers. The CAPTCHA is impossible to solve because my device (iPhone + Chrome using mobile site) can not copy the text required to be copied and pasted into the input field!
But after clicking "Copy", the clipboard is empty: Trying to paste never gave me an action option. The way to be shown an option was to type something in, select it, then long-press, but with the clipboard empty, "Paste" was not an option:
You'll notice too that when searching in-page for a character in the target, there are no hits highlighted.
Further, I have never been able to solve the "street signs" image challenge (I got through to the copy-paste on a food image challenge).
Example of failed "street sign" challenge:
And a failed food challenge:
Please tell me where I went wrong; I'm pretty sure I checked the correct images.
For comparison, here's the food challenge I passed:
This is getting a little silly.