For example, I spoke to someone (who I did not book) who was horribly disappointed in his last cruise. When I questioned him about, it seems he had been told (or assumed)that he would be on a 5 star cruise and would have multiple restaurants and entertainment options. Instead he was on a good middle of the road contemporary cruise line. It was one of their smaller ships, so didn't offer as many options as the line's newer and bigger ships.
I have had many clients travel on that cruise line and on that particular ship. Because they knew in advance what to expect they had a wonderful holiday.
Having said this, I do depend on my clients to let me know their expectations too! I can put you on a wonderful relaxing small luxury cruise, but if you were looking for lots of nightlife and entertainment you're going to be disappointed.
Once you're back it's too late to "fix" your holiday, far better to get things right in the first place!