Work to do what?

Well it does and it doesn't...you have many plugins for wordpress(one and most popular is akismet) try finding more but they will always come(i have 10+websites that have WP on them and i have lot of spam also), but akismet is good

It won't eliminate 100% of them (even Google's ReCaptcha can be worked around, I've studied the subject some time ago), but it will stop a lot of them. Another interesting way to go is a maths challenge, so far I've had good success with it.

Seb.

It doesn't stop them completely but you'll reduce your inbox that's for sure.
I'm seeing a lot of unique captcha's out there and it doesn't seem to be one kind of captcha anymore.

The term captcha may sound strange at first but honestly we're all using it everyday of our lives.