Poker is subjective also know as situational. There are mathematical correct plays to be made based upon EV and implied odds is one of the factors to be considered. Chasing a flush is good as long as you have the right pot odds. But, you can miss your flush draw 18 times in a row and make them 5 times in a row.
Pot equity for AA is only about 35% to 85% depending on the number of callers.
This intellectual exercise is great for my game - need to weed out the leaks. As said in the 'Serious Poker' book; thinking about your game away for the table helps you improve your game.
But, actually trying to define a hand or a series of hands a lucky or unlucky in a random universe is not easy at all.
Chaos theory as explained in Jurassic Park (cool movie). It is a random world full of random events.
As long as you are not being cheated and the game is fair then "shit happens" more than we would like but without an explanation such as "luck".
I believe in luck but I also believe that it can not be controlled by wearing you lucky shirt.

My definition of luck is after all the cards are dealt and I have made my hand I think that I was lucky. If I missed my hand I was unlucky.
The label of luck is assigned after the hand is over.
My 2 cents.
