[Nathan]

When I was living in Osaka, the only 大阪弁 word I really used was めっちゃ. Mainly because I liked how it sounded over とても. It just has more energy.

But there was a university student from NY in my area that I met frequently. He spoke amazing Japanese for a 21 year old, conversed freely with the natives. He was able to hold basic conversations in the Osaka dialect, but the bartender admitted to me later that he wasn't comfortable with a foreigner speaking exactly like a native and had been encouraging him to use standard Japanese instead, unsuccessfully.

It could be that some Japanese see it as you indirectly mocking them, like how some British people I know would hark on me for occasionally imitating their accent and varied vocab.