I already do phone translation for a living and really hate it. I'm only working for the money. I hated when my parents ask me to translate for them when I was a kid. My father already knew some English and would purposely made me translate a whole form. He actually interpreted things better than me, lol.
If someone were to ask me to teach them Spanish, I would tell them to look for a Spanish professor. Same thing if a native Spanish speaker ask me to teach them English... no thanks.
I don't really feel like I'm actually having a direct, normal conversation with you in neither case. It feels more like either a teacher-student relationship or I'm just acting like a 3rd party translating for you.
Same thing vice-versa... if you speak Spanish then ok I'll speak to you directly. If they speak a good level of English and just need a few corrections (nothing major) then fine. Teaching you how to pronounce even the A, B, C and everything from start... no thanks.
Superb Opinion