If your antenna can pick it up and the signal is strong enough, the Hopper's OTA module will pick them up and add them and integrate them into the standard guide (they show up in YELLOW, well, the call sign 'block' does).
If Dish carries the MAIN channel, the guide data for the -01 channel will be copied to that slot. And I'm repeating this on purpose, if Dish carries the MAIN channel, the guide data for the sub-channels will, by design, be populated. If the station changes the TSID, for example, Dish is no longer "fixing" these issues on their end. There's a long thread about this, well, it's about "requests" to Dish to fix that is going seemingly un-noticed by Dish... It's not that common though. As dwarren2 also mentions, it will populate the data for local channels from other markets as well, if you can pick them up. I'm in the Dayton OH market but I get most of the local channels out of Cincinnati OH (the UHF ones, none of the VHF because of my antenna) and my guide data is filled out.
If you have an independent channel that is not carried by Dish, you will not get their guide data.