@Anthea26
Regardless of whether or not it's icky (although it is, and most guests really don't like it), telling a guest you're leaving them 5 stars, and even hinting that they do the same for you, is considered by Airbnb to be Incentivisation, which is in direct violation of Airbnb's Review and Content policies, and can get you suspended or delisted.
Airbnb's Dispute Moderation For Reviews
Extortion and Incentivisation
Violations may result in the restriction, suspension or termination of your Airbnb account.
This policy prohibits:
- Hosts requiring a guest to leave a positive review or rating, or to revise a review in exchange for a partial or full refund, or a reciprocal review
Airbnb's Review Policy.
2. Reviews Should Be Unbiased
You are not allowed to incentivise positive reviews, to use the threat of a negative review to manipulate a desired outcome, or to influence another’s review with the promise of compensation.
Airbnb's Content Policy
The following content is never allowed on Airbnb:
• Reviews that are biased or exhibit indications of extortion/incentivization
Also, there are a number of viral news stories circulating at the moment, which are shining a very uncomfortable spotlight on all the (many) ways Airbnb's review system is being abused and manipulated for nefarious purposes, and gaining a lot of terrible publicity for the company, so you can be sure than any host who gets reported by a guest for even the most tenuous of review policy violations, will suffer harsh consequences. Truly, not worth the risk.