I find Alexa is getting worse and worse at understanding me. It used to be very accurate, and my theory is that since I first got one, there are now so many that the server can't cope. Alexa is also built into so many things these days, such as TVs and tablets.
For those who don't know, when you say something to "her" she doesn't do anything except pass it on to the "cloud" (in reality miliions of computers). The cloud then interprets what you said, finds the answer, converts it to speech and sends it back to Alexa. This is done via the internet, and may have travelled across the world and back to give you your answer. Hardly worth the effort based on the quality of her jokes if you ask her to tell one
Try it