Bad listing photos. Poorly executed (i.e., dark, taken from an awkward angle) and poorly chosen photos (of unattractive areas and things, small rooms). Only the best aspects of a home should be featured. More is not better!
Messy homes. No boxes should be on the floor, items should be put away, and it needs to be clean. The competition will be appropriately prepared so buyers will have difficulty looking past these things.
Overdone descriptions. Using fancy and unnecessary words. There is a brokerage that works my area that is famous for their hilarious “choose from a thesaurus” descriptions of ordinary items. One example is the word “alfresco” for any patio or outdoor living space.
Overly involved sellers. In one of my listings the seller wouldn’t allow a lockbox or let me set up appointments, but handled the calls herself. An agent called the seller and set an appointment, but the agent was so unnerved by that conversation that she immediately called me (to avoid having to talk with to the seller again) to cancel the showing.
Homes not ready for showings. Everything should be done, fixed or completed. When looking at a home while it was raining, my buyer and I found water running down a chandelier – with all its bulbs lit, into a bucket on the dining table. Needless to say my buyer passed on that home.