Well any painter would love to paint before floors go in to save the hassle of saving the floor all over. MY choice is to even wait until the floors are in before choosing wall color.

Been there, done that. Even dust free hardwood refinishing produces dust and wall marks. Floors first. Let finish cure. Then paint. New construction is easier. They spray walls, paint and then put in floors.

When installing or refinished HARDWOOD floors the wet work (drywall mudding, painting, backsplash/tiling) should be done FIRST.

Design-wise (as Patricia is a Designer extraordinaire) it is better to choose paint last. Using paint colours that coordinate with soft furnishings is always your best bet.

Good advice above!

Any wallpaper stripping or wall repairs should be done before the floor work. Floor work can affect the paint work around the perimeter. Painting of walls can be done before but I always recommend a coat be done after. Floor sanding is rough hard work. Herding a big machine around close to walls while it's hooked to a heavy 220v power cord and a dust bag or vacuum hose is difficult work and the quality of the floor sanding comes first. The edge sander sands right up to the trim with no guard so it's possible it can touch and mess up fresh paint.

Furthermore, people usually paint more frequently than they sand floors so painters are accustomed to working over finished wood floors, tile and carpet. If they're careless they won't stay in business very long.