Asking for side projects is essentially saying that you think the resume is a pack of lies from back to front.
My work is my work, and my play is my play, and I question the wisdom of judging the play in the decision to hire someone to work for you. Even when I do code at home, away from the office, I do it differently. It might be in a different language, for a different target platform, for instance. I might write more automated tests, because I can't hand it off to a tester that isn't also me. I might write something with a command-line console interface instead of a GUI, because my user base is probably just me, and I know that person is not a helpless idiot who can't read a man page--a man page that I probably will never write in the first place.
Real work is reading the crap code written by your predecessor, understanding it just enough to change something without breaking everything else, and moving on to the next thing as quickly as possible. No interview has ever tested my ability to read existing code or to alter existing code for a specific goal.
Whiteboard this: "This third-party data grid inexplicably causes all text typed into this column to come out backwards. You have 60 minutes to fix the problem, because code freeze is in four days, test needs at least a week to bang on a release candidate build, we ship at the end of the month, and you have 15 more equally-stupid issues waiting for you." And then you are judged on the quality of your horrendous kludge. Those companies that look for perfect people that write perfect code at work, then go home and keep doing it, are living in Cloudcuckooland.
Right now, my side project is getting the last two achievements in Fallout 4. After that, it will be banging out an entire novel in November. Or maybe it will be making furniture to hold DVDs, with a built-in system to deliver a painful shock whenever someone puts them back out of the correct order (which is sorted first by genre, then alphabetical by series name or title). Or maybe it will be working out a plan to terraform Venus using wormholes. When I leave work, I do whatever I want. I don't want to endlessly prep for an unending parade of stupid tech interviews.