Q: like i can't hear the difference in "correctness" between d7 and like, g7 if i were to fuck up and put my finger somewhere wrong.
A: actually, this is a fun fact about D7, G7, anything7, ...... those chords are founded on 'incorrectness.' it's kind of like the evil monster character in a movie. you may look at that character and think 'aah, ... scary'  ... but is that wrong? no it's actually very right for the movie, especially for the scary parts of the movie