When we see a large than normal spread, it can signal a run is about to take place.
It tells me for sure that the number of shares available are not in play. MM have a 3rd level that retailers can't see. We either have a large buyer hiding his purchase (only MM see) or the number of shares available is really thin. Meaning traders have pulled their offerings because someone is talking about the Nerdland closing.
Either way, when I see a spread increase, I place the stock on a closer watch level.