I think this is the first time that I've seen someone actually recommend encouraging the mariachi band to approach. Usually people are trying to avoid eye contact so the don't approach.
The cool thing is that if you pay them, you sometimes may be able to ask for a song that you actually like, and they might surprise you. A friend of mine was a mariachi violin player. He liked heavy metal music and played mariachi for money , but his band could cocee stuff like Run to the hills, ace of spades among others.
It's amusing if nothing else.
However, my partner is mexican and was pretty moved particularly by their playing. I've heard a few performances and that one was played with particular investment. It is a different vibe when a full band boards your boat. Of course, YMMV.