I will tell you that it does impact on your actions and in the vast majority of cases you are not conscious of it.
Interesting comment. Last night my CE inflight service was delivered professionally and competently, unlike the previous two.
But I did not see a single smile from the three crew in our cabin.
The flight met the standards I expect for service delivery and that is good enough for me.
On the CW flight, it was service as usual, with just one hiccup, the seat I was allocated had several large areas of dried white/cream stains on it. Fortunately there was a spare seat available for take off and then the CC member in my area (who was really nice, as well as professional) changed the cushion so I could return to the original place.
The contrast between crew body language and facial expressions could not have been more noticeable.
Edited to add that I am not saying the difference between the two crews was anything to do with the strike, just that we pax do notice whether crew are apparently happy/not happy.