There is a short, free mandatory trial period on every app in the play store.
The first time you purchase an app you have 15 minutes, during which time you can go back to the store and hit "refund" to reverse the charge and uninstall the app.
Yes, but 15 minutes is not enough time for me to evaluate an app. 48 hours would be nice. Best of all would be if the store allowed the app developer to specify how long refunds were permitted for (and displayed that information at purchase time). I think the better developers would compete to offer their customers flexibility, confident that their products would prove their worth.
So you use most of your games for less than 48 hours each? I'd say you're getting very little use out of them! But that's why I'd actually prefer that the developer got to choose the length of time that refunds were allowed. Then the person selling the quick game with a 20 min play time could allow only 5 min for refunds, while the to-do list application could have several weeks.
The first time you purchase an app you have 15 minutes, during which time you can go back to the store and hit "refund" to reverse the charge and uninstall the app.