A good question to ask if your boat is fairly common is "Are you familiar with this model boat....Have you surveyed one before?"
Most surveyors contracts preclude any responsibility for missing anything in their survey. That said...I had one refund my survey cost after missing an important flaw. My experience says that in most larger boats...a surveyor WILL miss some stuff regardless of how competent. As long as they don't miss IMPORTANT stuff...that is OK....they are human and bots are complicated.
A boat on dry land FOR A WHILE is better for a survey with regard to measuring moisture levels in the hull. You still need to do a sea trial AFTER the survey so the in water stuff can be checked.