| Does the value of XMR mined exceed the electricity consumed by the app? There are already malicious websites using hidden windows to mine XMR, but to the benefit of the person in control of the site rather than the people who pay the electricity bills: https://arstechnica.com/information-technology/2017/11/sneak... |
The answer to the question "should I mine [coin x]" in order to make money is usually "no". You should mine that coin because you care about the network's security and decentralization or not at all. If you have access to next-generation mining hardware or cheaper-than-normal electricity, you might have a case for "yes". Or, as you indicate, if you have a malicious way to run the miner or mostly-malicious-"not-too-clearly-disclosed-to-end-user", that is almost certain to make money.