@Sarah4157 You have really complimentary written reviews and even the one where she mentioned an odd odor is really positive, aside from that one thing, but I'm sorry she gave you a 3 star rating.
Quite honestly, plug in air fresheners are not okay in an Airbnb, nor are diffusers or anything like that. What smells good to you doesn't smell good to everyone- personally I hate the smell of lavender, and so do several other people I know, and if I arrived at a listing and found any kind of air fresheners, I would cancel and leave.
An Airbnb should be as scentless as possible.
I see that another guest mentioned the dog smell, so maybe you are trying to cover up the smell of dog with something else, but that doesn't really work. Dogs and carpets are a bad combo, but it's your home, so that's how it is. You may need to shampoo them more often, or sprinkle baking soda on them, let it sit for awhile, then vacuum. But don't try to mask the smell of dog with something else. And whether the dog goes in the guest room or not won't prevent the carpet in there from absorbing the odor. We get immune to the smell of things we're accustomed to.
Asking for a 5*review is not okay and can easily backfire, but since you are a home share host, you may be able to bring up the subject of reviews in the course of other friendly conversation with guests. I sometimes do this, but I speak about how Airbnb presents the star ratings differently to guests than they apply them to hosts. I never ask for a 5*rating, because frankly, ratings aren't a source of stress to me. I even say that a guest should feel free to give whatever rating they feel a place deserves, but that what is disturbing to me is that guests are led to think that giving a 4* rating, which Airbnb tells them means "Good", is considered a "needs improvement" or a "fail" when it comes to hosts. One guest told me she had been giving 4*s for places and hosts she really liked and would book again and was shocked when I told her a host will lose their Superhost rating for anything under a 4.8 average. She just didn't know and thought hosts would be pleased to get 4*s.
Do try not to take the star ratings personally- they are very subjective and really don't mean much. People are fickle and some guests actually say they never give 5*s because that means perfection.
Good written reviews make more of an impression on guests than the star ratings. They really don't care if a place has a 4.9 rating, or a 4.5 rating, if the price and location is right, and your written reviews make it clear that your guests enjoyed their stay. And the occasional comment that isn't glowing is fair enough as long as it isn't a lie, and will either be something you can try to improve on, or not.