I just discovered people are earning money doing 'captcha work'

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I am familiar with being paid to read emails or to click offers (not that I have ever done either), but surely if you are completing captchas, you are aiding and abetting spammers?? I struggle with many of the 'paid to' schemes that are abound, but surely paid to complete captchas is morally the worst type of paid to?? Or is there a side of this that is legit??