I am amazed by how many houses go on the market completely unprepared for the most common action prospective buyers make. Buyer open everything that is closed and you want them to because this is how they start to imagine living in the home.
Expect that every drawer, cabinet, and closet will be opened and viewed. Buyers are not apt to riffle through your underwear drawer but they may very well open that drawer even if it's not built into the house. The line between personal possessions, staging items, and what actually goes with the home gets fuzzy for buyers who are excited about the property.
Ultimately your goal is create an atmosphere whereby potential buyers to feel completely at home. The simple solution is to make sure you are prepared. Pretend you are in the army and could have your barracks inspected at any moment.
When you are selling your home, the time to de-clutter is before you go on the market.