Every time I see someone call their guitar anything like "bad girl", I can't help but imagine a dude that is visibly extremely single and/or old and quite round. Either that or someone trying very hard to sound/look "cool", and everyone but them can see that they're failing at it lol. It never doesn't come across as super cringe, just like when people call it an axe or give their guitar a name that they insist on referring to it as. It's an instrument and a tool, not a pet or a person haha.

All that being said, nice guitar! (which incidentally would've been a perfectly good and preferable alternative to "bad girl" lmao) "Brought this nice guitar home with me yesterday".