Android phone taps touchscreen on its own I have an LG P690 Optimus Net. The issue I am having is that the phone often enters a state where it keeps on pressing the touchscreen's buttons by its self, and I have to press the back button several times to try and go back while it keeps opening new screens or entering text on its own.

I was wondering, is this something anyone else has experienced? How common is this defect, and has it to do with Optimus Net phones or with phones in general? Are some line of products more susceptible than others? If common then how does the problem I just described typically arise? Could accidentally dropping the phone or humidity in the air cause it for instance?
Yes. Seems there is a problem. The touchscreen takes inputs that was never made. Have a look at this http://www.thinkdigit.com/forum/mobiles-tablets/122921-official-android-discussion-thread-73.html#post1836923

There are various problems of Android that LG ships on the P690. I'd suggest installing a good custom ROM, which should fix the problem if it is not a hardware issue.