If you are referring to the Hubpage's Earnings Program, they state:
"Advertisements from the HubPages Earnings Program will appear on Your Hubs at HubPages’ discretion (and such advertisements may appear on every page load of your Hub)".
It is found here http://hubpages.com/help/user_agreement under number 9, under the Hub Pages Earnings Program section, and it's the 4th bullet point down.
I'm sorry to be the bearer of unfortunate information. If you are concerned about competitors, then perhaps starting your own website would be more advantageous?
Don't get me wrong as you could still find a way to use Hubpages in conjunction with your own website; but perhaps the hubs here then wouldn't be as affected by competitive businesses if they concentrated on your business and your services instead in hopes of directing traffic to your external site. That might be a bit taboo, but it's just a thought....