A seedy person or place looks dirty, tired, and a bit poor — and often feels shady, as if something illegal or not quite decent is going on. A seedy hotel has stained carpets and a lock you do not trust; a seedy bar is run-down and linked in your mind with drink, sex work, or small crime. Calling a person seedy is unkind: unkempt, not respectable, maybe not honest. It is informal, a little old-fashioned, and stronger than just “messy.” Though actually, seedy first meant “full of seeds.” The dark meaning grew from slang for “poor, out of money,” from the picture of a plant that has gone to seed and is no longer pretty. From there it spread to unwell or past-their-prime people, then to run-down streets. You can still meet the older “full of seeds” sense, and some people say they feel seedy when they feel rough and unwell, but the meaning you will hear most about people and places is this dirty, low, slightly criminal one.