In general, any PoW-cryptocoin quickly reaches an equilibrium with its costs. Changes in the difficulty, changes in the exchange rate (usually as a function of changing demand), changes in availability of current/next-generation mining hardware will destabilize this equilibrium temporarily.
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.
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.