Is a full fare myki still a valid ticket if you are obviously eligible for a concession or special myki?

i am considering getting a full fare myki while eligible for concession as i heard the ticket inspectors target concession mykis hard, and you may need to go through hassle to get certain ID to use a concession myki. which doesn't seem worth the discount

But if you are obviously eligible for some kind of concession (student, senior, child, whatever) is using the full fare myki fineable? and would authorised officers try to target you for this? i couldn't find any information about this

has anyone actually done this?