Folks may fight dirty, but there is a better way, to fight decisively.
Those who fight dirty do so because they really cannot fight at all, so they rely upon cheap tricks and deception to win a fight.
Actual warriors doesn't need to deceive their enemies because they know how to fight, cannot be bested by deception because they can see right through it, and never drop their guard, leaving no opening for a suckerpunch, a kick to the groin, a poke to the eye, or a stab in the back.
Dirty fighting is only employed by contemptuous cowards which can only succeed against like-minded individuals who fail to recognize, analyze, and neutralize a threat without hesitation before it has an opportunity to strike, because they lack any skill, instinct, or spirit for fighting.
Fight dirty if that's the most that you are capable of, just don't be too surprised when it fails spectacularly when attempted against anyone with even the most miniscule of combat capabilities, or if a true warrior simply recognizes you as a threat and makes short work of you before you ever get a chance.
Otherwise, I suggest actually trying to become educated in the art of fighting, to hone your skills, sharpen your mind through experience, and seek out your fighting spirit in order to overcome your fears as well as your doubts so that you can fight decisively.