How do we prevent phishing bots and spammers from filling out our forms?

Thank you. I wrote that out of frustration/humor, but I'm not completely helpless. Possible solutions include:

1) Creating a "honeypot" or hidden field that filters anyone who fills it out to a Smart List for deletion Stop 99% of Your Spam Leads with Marketo | Fab Capodicasa | LinkedIn

2) Adding CAPTCHA - MktoForms2 :: reCAPTCHA  (your link from another article)

3) Hiring a web developer - Add JavaScript validation to the header of your landing pages. This checks to see if JavaScript is enabled on the browser - and, if not, redirects the lead to a page that advises them to do so. Spam bots do not have Javascript enabled.

4) Adding a script that restricts certain parameters ex. Email Domain http://developers.marketo.com/blog/restrict-free-email-domains-on-form-fill-out/

While all of these are valid solutions I still find myself a bit lost here. My personal solution for the time being is to take the Smart Lists that I've already created (This article is helpful for setting those up - http://developers.marketo.com/blog/how-to-clean-your-marketo-database/ ) to identify the spam leads using several filters and simply add a Flow step to delete them as they're identified.