Because your Realtor is smart! A house that isn’t neat and tidy will not show well in pictures online.
Most people start their search for a home on the internet and if they see pictures of a home that isn’t well cared for, they’ll wonder how much deferred maintenance there is that they can’t see. Also, a messy home is an unattractive home.
If you want top dollar for your home, don’t be lazy and thoroughly clean it up and keep it that way. It will pay big dividends in the long run.