Personally, use caution when using a service that generates fake reviews or downloads. I work for Apptopia, an online marketplace for mobile app acquisitions and sales. Basically, we sell the whole app as a business to either another developer or an investor. Part of our service is to offer a free app valuation, where we recommend a reasonable price you can expect to receive for your app, and we take into account revenue, downloads, reviews, features, design quality, etc. As a company that deals with lots of apps, we’ve done the math, and on average, downloads-to-reviews come in at around 50-55 downloads/ 1 review. Obviously this varies, but if you come in with a 20-1 download to review ratio, something isn’t right. As a side note, I have yet to run into one of these review companies that generates even mildly convincing reviews. They don’t use your app, and the reviews tend to reflect that. Just a heads up!
I have to say buying fake reviews is a shady way of marketing but it could also be a necessary corrupt one:( Here in Asia, this is called “Shuabang”.
It’s so popular and not cheap that few small developers could afford it. This is unfair though. Here is an article on this “marketing method”. Shuabang vs United Mobile Games: Yang Wang Weighs In
Also are your apps for android or for iOS? As far as I know there are pretty some app optimization services especially for iOS apps like optimize your app description, app name, etc…
See here are a list of some big companies working on this: Top 10 App Store Optimization Companies in 2013