Er... One obvious thing "more unattractive then a saddle bag on an otherwise nice bike" that immediately comes to mind is a cyclist, who looks like he just pooped a huge load into his jersey's back pockets (yes, on an otherwise nice bike). Although I have to admit that most of the time I find such cyclists hilarious rather than unattractive.More seriously, I cannot think of anything more unattractive then a saddle bag on an otherwise nice bike, but that is just me. Am I vain? Maybe but not enough to carry latex gloves..
The thickest (and the heaviest) thing that is allowed in the jersey's back pockets is a cell phone. Anything thicker and/or heavier is strictly prohibited. If you need to carry anything else (like spare tube, inflator, etc.) saddle bag is mandatory.