I went into Fashion Sense with the impression (from, oddly, the not-really-canon City of Clipsville ep) that of her sisters, Bubbles came off as the only one able to maintain a coherent conversation with the opposite sex (when it came to dealing with boys in a romantic sense). That morphed into this whole character interpretation of mine (not that I'm laying claim to originating it, mind you!) that Bubbles is better with people, that even when she's flustered she still comes off as adorable rather than dumb/ditzy, and these two qualities combined would give her an edge over her sisters when it came to flirting/maintaining boy relations.

Whiiiiiich obviously didn't all make it into Fashion Sense, it being so short, but it pretty much stuck with me ever since and continues on in TEF :D