@Susan17 As I host a private room in my home, with a 3 day minimum, I generally have a fair amount of interaction with my guests. I do bring up reviews at some point, and I do tell them how Airbnb applies the ratings to hosts, while leading guests to think that 4*s is a fine rating to leave. I haven't had any guests express any discomfort with this information, either verbally or through body language or facial expression, and I'm pretty good at picking up on that stuff. To the contrary, guests have thanked me for letting them know- some say they've rated perfectly nice places, with nice hosts, where they would book again, at 4*s, thinking that was a good rating, and were horrified to find out that that could tank a host's ratings or cause them to lose Superhost.
I certainly don't go on any long rant, nor tell them to leave a 5* rating, nor tell them I'll leave them one if they leave me one, none of that. I just convey the information. Some of these guests have been considering hosting themselves, so they were quite grateful for the info.
Of course, if a host doesn't feel comfortable talking about this to guests, or even leaving the info in the house manual, that's up to them- we're all different in how we host. Also different in being able to talk about something like this casually, and then just move on to some unrelated topic of conversation. And not everyone has the same amount of interaction with guests and some guests only stay one night- in that case, I think it could be awkward. But my guests stay for at least 3 days, and up to 2 weeks, so over that amount of time, we might engage in several hours of conversation over coffee or a glass of wine, of which the review discussion might take up a total of 5 minutes.
Just wanted to say that in my experience, no guest has been offended by review talk.