Feeling guilty about it is just silly. If you don’t want to “cheat” into certain skills don’t use injectors. It is as simple as that. I promised myself not to use injectors for the simple reason I want to grow my characters including making bad decisions in skill training. It makes the characters feel more “alive” to me in the role playing part of the game.
I don’t like the fact CCP introduced skill injectors to the game even if i do understand the reasons why. In my opinion time spend on skill training is an essential part for full immersion into the game. To me EVE is not a game suited for immediate gratification but a journey which takes many months–>years and every day of that journey is an adventure in itself.