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Lol. Do you have an active interest in fire hydrants? Maybe you might be on to something there though. For instance, it asks you a question or shows you an image you should be familiar with based on your browsing history/cookies (though maybe this is too Orwellian for some). So, for example, it could show users here a bitcoin logo and ask you what that is. Obviously, people here would know what it is but bots of bypass farms wouldn't.
If I were to activate the tinfoil hat mode I would say it was because I read this topic yesterday night and they've updated my profile, > this guy is definitely into hydrants.
For the second part, if the answers are Bitcoin, Bytcoin, Bitcoin, Botkin I doubt we're going to see accuracy over 90%.
I've been thinking that you could maybe make a better and perhaps less frustrating captcha by showing people a randomly-generated inkblot, asking "what do you see?" with a free-form text field, and comparing their response to everyone else's responses to that inkblot, using the same principle as recaptcha.
In the case of a smaller website, with only a thousand or so people getting captcha couldn't that be exploitable by waves of bots coming in and on purpose making thousand after thousand of wrong answers so although it looks like a butterfly 99% of the answers are going to be squirrel droppings?