I just bought a condo that is one year old. There's primer on the wall without paint for one year. Should I do some light sanding and then paint it? Or should I just clean and wipe down dust on the wall and then paint? Or are there other suggestions? Thanks guys.
Clean it well (e.g. with a TSP substitute). Assuming it is still adhering OK to the drywall, there is no reason to sand or prime again.
I'd go ahead and paint it as-is, just as I'd paint my living room after a year, or ten, without any special prep. Kitchens with evidence of grease should probably be cleaned locally.
I've never had paint fall off yet after dozens of personal and professional projects over several decades. Modern paints are very good.