How do reviews work?
Only guests who actually took a trip can leave one, and every review is read before it is published. Critical reviews are published; that is the point of having them.
A review can only be written against a booking recorded as completed, so nobody can review a trip they did not take and no competitor can post about your boat.
Moderation removes phone numbers, personal details and abuse. It does not remove criticism. A one-star review describing a genuinely poor day will go up.