Will Google suspect that useful links on our site are paid?

On our travel site, we recommend and link out to hotels and B&B’s in our niche. Our readers find it useful. They’re not paid links, so we don’t add the nofollow attribute. What stops Google from suspecting these are paid links and penalizing us?
Greg M, Vancouver, BC

Have a question? Ask it in our Webmaster Help Forum: http://groups.google.com/a/googleproductforums.com/forum/#!forum/webmasters

Want your question to be answered on a video like this? Follow us on Twitter and look for an announcement when we take new questions: http://twitter.com/googlewmc

More videos: http://www.youtube.com/GoogleWebmasterHelp
Webmaster Central Blog: http://googlewebmastercentral.blogspot.com/
Webmaster Central: http://www.google.com/webmasters/