I was just behind the times when it comes to robots.txt. I didn't know about it until today (I thought the meta tags controlled these things). Anyway, I found this help page:

How do I block or allow Googlebot?

Based on this, I think this what I should put in the robots.txt file of my ministes:

User-agent: Adsbot-Google
Allow: /
User-agent: Googlebot
Disallow: /
User-agent: Googlebot-Mobile
Disallow: /
User-agent: Googlebot-Image
Disallow: /
User-agent: *
Disallow: /robots.txt


This will allow the google adwords bot in (so I won't be penalized for adwwords quality score), but it will keep other bots out so I won't be penalized for duplicate content in relation to SEO. I put Disallow: /robots.txt line so that the robots.txt won't get indexed and cached. If I'm not understanding any of this correctly, please let me know.