I remember that Darkcoin had a few incidents back in the day where people were running cpu-miners and later on gpu miners on the victims machines. For instance see this reddit post about a cpu miner back in 2014: https://www.reddit.com/r/sysadmin/comments/28klfl/disguised_mining_process_using_up_99_cpu_on/

I made a really quick google search for malicious gpu mining on gaming rigs, but I did not find what I was looking for. Maybe others remember this. People were installing some popular game, but in the background, they were mining darkcoin at the same time on their beefy gaming rigs.

So yes, all coins have this "misfortune", but anyone can install a piece of software and start mining on a pool, it's not that hard really.
Today it might not happen with Dash due to asics and high difficulties, but still sometimes people come up with the clever idea of cpu-mining bitcoin so you never know....