When I was a teenager, a friend's father was a contractor, and once in a while during the summer he'd take my friend and I to do odd jobs on a job site for a little spending money. Time and again he harangued us to leave the workspace clean at the end of the day even if we'd be back the next day, insisting that it was important to making a good impression, but it just struck us as the kind of thing adults yelled at kids. He also insisted a swept floor was the single most important aspect.
One day, we arrived early on a job renovating a church, and did a bit of finishing up of things we'd been doing the previous day, and were expecting a delivery of tiles that we'd need to complete the next step of the project. It didn't come, and we ended up sitting around, and it still didn't come, and we went down to some nearby tennis courts and goofed around playing tennis and ogling the girls who were playing tennis, and then we listened to music a while, and still the tile didn't come.
When it became clear it wasn't going to arrive at all, instead of leaving way early, my friend's father insisted we spend most of the remaining time doing a very thorough clean. We groaned about it, but even so, we'd gotten to dork around most of the day and would still be leaving a little early, and the pay was the same, so we couldn't complain too much.
As we were leaving the guy who'd hired us happened to run into us on the way out, and took my friend's father aside, and complimented him voluminously on how well the job was going and how much we'd gotten done. He even commented specifically on how productive we'd been that day. Well, my friend's father crowed a bit about it on the way home, but he didn't have to -- a demonstration proved more effective than all his preaching.
So whenever I do work in my workshop, I try to always leave it clean, even if the project is still underway and I have to leave a bunch of stuff out to resume work the next day. And I especially make sure to sweep the floor. Whether I've been productive or not, I always remember: a clean workshop gives more of an impression of a productive workshop than a productive workshop does.