So, let's take a look at this example. Clearly not a good game from a subjective point of view, and the overall review is at 3 stars. Their fb page has 5 likes, and this is their website.

Obviously this isn't going to be a big hit or anything, yet it has 50k+ downloads on Google Play Store, and it is ranked 39 on the new released chart, which is much more than what I can say about my first game.

What in the world are they doing that I, and I assume many newbie developers, are not doing?

Some games do it by advertising or by leveraging their social networks.

Some games do it with botnets.

What in the world are they doing that I, and I assume many newbie developers, are not doing?

Paying 3rd parties to artificially inflate your downloads? They haven't yet paid for thousands of facebook "friends" and twitter "followers".

I'm pretty sure it's against iOS's, Android's, Facebook's, and Twitter's terms of use, and if caught, they'd be penalized in some way or another.