Practicing sloppy chord changes is not doing you any good.
The one minute changes exercise is to learn to change chords quickly so you
can play songs.
Should i be doing my 1 mi ute changes slower if it meens ill have better sounding chords.
Yes. Justin say not to count sloppy chords so if you doing 10 sloppy chords for every 10 good chords
you only count the 10 good ones. So it's better doing 15 good ones than 10 bad and 10 good.
Justin also says "Practice make Permanent" so the more you practice sloppy chords the better you learn
to play sloppy chord and the longer it will take to fix the bad habit.
You do need to push yourself so do practice at a higher rate than your are comfortable doing.