Oh that's easy, people will more often criticize and complain then they would compliment. Now they may not sign up for a fan based site like this but I 100% believe they would get on tripadvisor or yelp and scream bloody murder.The couple is too lazy to do their homework before going to Disney. What makes you think that they'll have the drive to go to a message board, make a username, and write out coherent paragraphs? If they were that kind of person, they would have researched and learned about WDW first.
Next who says all complaints are written on fan boards, word of mouth, facebook and twitter are massive. lol heck, twitter is now the politicians complaint board of choice.
Heck you see it here, people will post all the day what they hate about Disneyworld and when you question them on it, such as why they continue to go, they will say "oh but we had a great time"!! REALLY?? when? what part?. lol, you never hear them compliment or post a trip report but they'll complain all the live long day.