[kevin_p]

Just because something is checked client-side doesn't mean it's only checked client-side. I've used JS checking on anti-bot questions[1] quite deliberately: it doesn't have any effect on 99%+ of bots, but it stops posts by humans from accidentally being flagged as spam.

[1] admittedly questions like "type someword in this box to prove you're not a spambot"[2] rather than actual captchas, which I agree would be rather silly.

[2] if this is what you meant by a "printed in plain text in the source code" question, remember that most spambots aren't customised to an individual site, they just roam the internet submitting their crap to anything that looks like a comment form. Sure, it's trivial to write a script to parse the page and find the answer to the question - but nobody's actually going to do that for a typical company's "Contact Us" form. Adding this sort of check cuts down on spam enormously (from hundreds a day to zero), and is way easier for humans than solving a captcha.

[__david__]

> admittedly questions like "type someword in this box to prove you're not a spambot" rather than actual captchas, which I agree would be rather silly.

This is not silly. This works extremely well for the low traffic forum I run. Since there are a huge number of phpbb3 forums out there, spammers have made spam bots specifically targeting the platform. If you make your forum epsilon different from the default then the bots don't work without manual intervention. That's enough to keep you off of autospam lists for very, very long periods of time.

And when someone inevitably adds your extra form element to their spam bot (it's happened to me 2 or 3 times over about 6 years) then you just change the answer and it stops working (and they might not even notice since it's a bot).

[kevin_p]

Updated to be clearer about this. I meant that fake captchas like the one in the OP (which put HTML text on top of a confusing background image to make it harder to read) were silly, not simple question checks.

[wilfra]

Same! I was getting 50+ spambots a day registering to my vbulletin forum, even with a really hard captcha. I changed it to a question any eight year old could answer and I instantly went to less than one spambot per week getting through. Easier for users and nearly eliminated my spam problem, win-win.