Photos and promises are one thing; seeing actual finished work is another. A completed project is like the contractor’s report card. You can look at joints, alignment, finishing of edges, how neatly tiles meet, how carpentry has aged after a year or two.
You also get a feel for their style: Are they careful with details? Are corners clean or messy? Do doors shut properly? Does paint already look worn or still fresh? Talking briefly to the client, if possible, gives extra insights about punctuality, responsiveness and after-service.
Anyone can show a fancy portfolio on a phone. Standing in a real home they’ve worked on makes it much harder to hide sloppy habits. It’s like reading reviews, but in 3D.