You really do not need a Richard Dawson of the old 'Family Feud' show to disclose that answer. This is what Hotel Guests rate as the greatest testament to a memorable Experience - cleanliness, as reported by Kitty Bean Yancey of USA Today.
"It's cleanliness, according to a survey of 1,000 people just released by the Chubb Group of Insurance Companies. A whopping 43% chose that, meaning that a dirty bathroom, dust and maybe bedbugs are more pressing concerns than price (23%) and location (19%). The survey was conducted by Caravan Orc International, an independent public opinion and market research firm, this month." You can dress up a Pig, but it is still a Pig!
It is so basic, but Cleanliness is the Value Prop. We spend so much time and money crafting the message, marketing like crazy, "smoke and mirrors" magic for many. "Heads in beds" is our Mantra, but those "heads" may never return, and they will relate their Experience to others - bad news travels quickly and pervasively, our delivery slips and our reputation dips, too.
Attention to detail, follow those protocols and standards, train your staff - you cannot inspect Quality factors into the product. It is the process, the dedication, your philosophy (follow-up and follow-through) which makes the grade and the memory.
There are tools out there to help you evaluate your status. Naturally, create that relationship with your guests through Feedback mechanisms. Talk to them, seek their comments and opinions, bring them into the family, for they do want you to succeed. Have a solid Quality Assurance program in place, where you have the finger on the pulse of your operation. Mystery Shops can give you that "picture in time". All insight you gain must be timely and actionable.
Remember the Hierarchy of Needs, as established by Maslow, from your basic Management courses? It is applicable. You cannot build your pyramid of success with faltering tiers, especially if the foundation is shaky. The top goal, what he called "self-actualization" and you might call an extraordinary Guest Experience, simply will not be attained if the Guest Room or the bathroom is not clean. Time to return to the basics.