Tim Armstrong is a Malware Researcher at Kaspersky Lab. He is wary of the advertisements you follow within your favorite apps. If you would like to support an app developer, consider buying the paid version, if it s available. Use your best judgment to avoid being ripped off by following the adverts on your favorite app. This type of advertising will only give people a bad feeling about your app. It will even offer to dial for you! It is a simple bait and switch scam.
Source: https://threatpost.com/deceptive-app-ads-hit-users-draw-something-041112/76431/