I know you say that you don't have the patience to check every horde for their ability, but it is the most reliable way of checking their hidden ability. Moves like Worry Seed and Entrainment tells you what ability the target Pokemon has, but it is very time consuming to check each and every Pokemon in every horde you come across. Still, if you desperately want a certain ability it is the most reliable way.
Sometimes there are other ways, depending on the ability you are looking for. For example, Whismur has 2 abilities - Soundproof and Rattled. Growl affects all enemy Pokemon at once, so you can use it and see how many have Soundproof. Those without Soundproof must have Rattled, their HA. But not every ability can be tested like this. Even once you determine that a Pokemon has their HA in a horde, you will still probably need to use Worry Seed to find out exactly which one has the HA, but at least you don't need to check for it in every horde.
Personally I actually like hordes. While, as you say, they can be annoying and the Pokemon are weak, I actually like them because it appears that GameFreak are making Hidden Ability more accessible than they were in Gen V, which can only be a good thing.
