How reliable are modern LCD televisions?

Yup. can on mine.But it’s unnatural.
First thing I’d do is set it all to defaults, turn off all pixel processing nonsense and turn sharpening right down. Then tweak from there.
But it’s all personal taste I guess.

conditions in a shop are different than in your front room – much brighter, flourescent lights, etc

The point is that you want to make you TV stand out, so contrast/brightness, etc are all too high.

Not so much nowadays I think – in the old days of the Sony Trinatron they were so superior that they could easily out contrast everything else and therefore stand out, everything else would saturate and look nasty if it tried to compete.

Most LED/LCDs will look pretty nasty if you push up the settings.