I've been thinking about things that make it feel not 'Shabbosdik' for me, that don't have an actual halachic or minhag-based connection to Shabbos.
For example, we had a guest for Shabbos who wanted the hall light to be on. I never have that hall light on, on Shabbos. Seeing it on, gave me a "weekday feeling." Likewise, one Shabbos when we were home but had a simcha we were attending elsewhere, and I did not use the blech, it was odd to see the stovetop.
So for me, a routine in how my home is physically set up on Shabbos, makes a difference. I don't know if they sell them anymore, but many years ago, Bubbies had toaster oven covers, blender covers, phone covers, that they used for Shabbos.
I think many people feel that way about food (as in this post:
here about Pesach food ). There are those who make the identical Shabbos menus week after week, because in their communities these traditions are important. For the rest of us, we have all kinds of dishes that nobody in our past history ever ate on Shabbos or even on weekdays. And yet, there are certain dishes that, to me, are weekday fare. They don't seem 'Shabbosdik' to me (see
here about whole wheat challa).
I shut the ringer on my phone every erev Shabbos. If I am in someone's home on Shabbos (or Yom Tov) and hear their phone ring or their answering machine, I find it a jarring, unpleasant intrusion into the aura of Shabbos. Similarly, but to a lesser degree, when I hear loud music playing outside, usually from a car driving by or waiting at a light, it's an encroachment on my Shabbos space.
Walking in a non-Jewish area where stores are open would be another example.
And one more - I asked someone what makes it not Shabbosdik for them. The answer pertained to Rosh Hashana: seeing someone reading a novel Rosh Hashana night.
Do you have any examples?