If you want to get screwed, tell your surveyors how to do their job. If your engine guy wants to be there for the boat haul out then I doubt pictures will be acceptable. The hull surveyor is going to sea trial the boat. The seller might not be too keen on two sea trials.
I am curious what the surveyor found on the last boat. I have only once seen a boat that failed survey. Serious bottom blisters were found when the boat was hauled out. Almost everything else can be repaired by the seller.
When boat "shopping" we found a boat that we liked. I was not as knowledgeable then as to "some of the warning signs" as I am now. The boat "failed" survey and we walked away. I am now, very happy that I did not buy that boat and feel that the money on the surveyor was well spent!
The first issue that was of concern was the listing broker. He would not allow us to involve our own broker (who we had been working with for a while). Second, there were a few items I did "catch" on my own (that neither the broker nor seller had dealt with) that were pretty obvious. For instance he stored both a gas container and a spare propane bottle in the lazerette under the cockpit floor. Bad enough that this was an enclosed space, but it also contained 2 batteries (in series) and a battery charger for powering the stern thruster. The broker removed the flammables prior to the survey. I also spotted a couple of "easily visible issues" with the engine. The gear oil cooler was leaking saltwater right over top of the airsep filter and there was visible "crud" in the Racor filter. Both of these were corrected (at least visibly) prior to survey. Were these an indication of "general" engine maintenance?
Anyway, the reason the boat "failed" survey was that one of the stringers had separated from the hull and was not repaired in a "proper" manner. The surveyor was not the only one who felt that way, as I sent several good photos of the "issue" to the original boat manufacturer who was extremely helpful with suggestions, answers, and advice.
The broker told us that "stringers were not really important" and we shouldn't worry (his first comments), but later said that the seller would not drop the price nor would he repair the issue to our surveyor's satisfaction.
We walked, really glad we did, and I would not use that broker (even though he has the "certification") ever again for anything.
As an aside, the broker we had been using as a buyer's broker still helped us with advise and even research during this situation even though he would not have received a "commission" from that sale. I would have given him a "gift" (cash) for his help if that sale had gone through. Later he was instrumental in the completion of our purchase of Pilitak and we are FAR better off than if we had completed on the other boat.
I agree totally with what others have stated. Do as thorough an inspection on your own as you can. Don't go just by the "cosmetics". Then if a boat fails survey, think of it as "money well spent" as you could have ended up an expensive mistake.