sad to hear so many people shying away from legal but unorthodox tactics, and choosing to call them "dirty"..... kind of funny that submission grappling in particular is geared toward causing so much pain so as to make a person submit, or to choke the life nearly out of them....
This issue is simple. Obviously there are tactics that are illegal in the sub grappling realm. We all know what they are. There are lots of unorthodox things that can be used to make people uncomfortable enough to open up the sub we are looking for that will cause a hell of a lot more pain and danger for the most part. And some people don't call that "clean technique"....funny.
If you don't practice these techniques in practice when will you learn to perfect them? In tournaments?....sorry, it'll be a little late for working on them at that point.
There is also a way to use certain unorthodox techniques that is VERY abrasive and disrespectful, but still within the rules. For the most part, unless you are training at 100% with prior consent to do so, and you know your partner, then you usually won't want to apply things in a disrespectful or mean manner.
There is a technique is use in competition to open the guard that is very violent and scary for the opponent to experience. Nobody is expecting it and it happens quickly...it's not something i regularly pull out in practice, but at times if i've asked a partner to just go very lightly b/c i'm sore, and they proceed to go full speed and power trying tear into subs, then yes i will start getting a little nasty.
learn unorthodox techniques, and use them with good common sense. Realizing that this is submission grappling. stop listening to these BJJ only guys who believe that you shouldn't have to barely exert any effort if you are using "proper" technique and have set everything up the right way. Reality against a good fighter is almost never like that.