"Fred, stop trying to turn the internet into a toll road! ;-)" - Dewster
Dewster, it is already a "toll road" - only, at present, it is spammers and those who sort out the mess when some villain corrupts your computer, who collect the "toll".
I personally would much prefer the "toll" to go to those who host useful (essential) sites like TW, and perhaps gives them a little return for all the hours they must spend weeding the crap (planted by those spamming Aholes) from the forums.
I do not have a problem with "captcha like" filtering, just have a problem with ones that require the sort of visual perception that captcha does.. I understand the mechanism - the visual image is not easily deciphered by a bot.. Alas though, in this respect I am impaired in a similar way.
If there was an image which was not distorted, and had (for example) a simple arithmetic operation to which one gave the answer, that would be fine..
But I think the problem is that captcha is available and can be easily plugged in, wheras these other ideas would require development of unique code.. I think that almost any unique method doing what captcha does, would work - provided it was not widely adopted by other sites.. "They" are not going to modify the bot just to get TW, but when (like captcha) a lot of sites use the same filtering method, then it is worth "their" while to hack it.
Fred.