Way back when (October 1988) Terry was finishing up a trade mission in Lisbon, and since it was her birthday I ran over to celebrate and to spend a week or so in Portugal with her after she finished her work. It was her second trip there, my first, and she was excited for us to go to a Fado restaurant that she'd been to before on recommendation of the US Embassy staff. It was a memorable night. This is really a unique form of entertainment and the place we went (can't remember the name) was just excellent. The food was "Portugese peasant" (chicken in a pot) and I still reflect on it fondly.
Since then, I have made cursory inquiries whenever we've stopped there on cruises to see if there was any daytime Fado, but the answer has always been no. It is culturally very much a nighttime thing, as you can imagine since you know the music. And of course the locals come out in droves for it, everybody has favorite singers whom they follow like rock stars. The night we went, at a particularly emotional moment in one woman's song, a fan near us stood up, held out his hands and yelled, "Oh, LENA!!!" I think he had a "religious" experience. We learned that the most popular performers actually sing at up to five different restaurants each night. There's a complex schedule, and they really get around.
But of course I'm not saying that I'm certain that a daytime performance doesn't exist. There could be some tourist version somewhere in the city, but nobody I've ever asked has known about it.
Unfortunately, this is one of the big disadvantages of most cruises: you have no opportunity to sample the nightlife.