"Among the people gathered around, you see a tomato seller hawking his wares."
Next thing I knew, the PCs would be interrogating the tomato seller to see if he's some sort of spy. Or they would side-track thinking it was something important. Or they might simply side-track and attempt to haggle with the tomato seller.
On the other hand, if you're comfortable improvising stuff on the spot, you could simply roll with it.
I've found that sometimes, if the players find a detail that you've provided simply as window-dressing interesting enough to spend time interacting with it, it may be a good idea to reward them by turning it into something important.
This will not always work, but when it does it's very gratifying both for the players and the DM. I've had game session getting completely 'derailed' by what was only planned as yet-another-random-encounter, but great fun was had by all.
Having said all that, in Clarabell's examples I can fully understand the players. The hints were too subtle. Unless the players know your DMing style very well, there's really no reason to suspect a secret meaning behind every detail you provide.
Actually, we had a player in one of our game groups once who asked for details about absolutely everything, e.g. the exact angle of a hill's slope or the shape and materials a chest was made of. It always took ages for him to make any kind of decision.
The annoying thing was that he never actually did anything with the additional information!
He typically just moved on, his curiosity satisfied.
Interestingly, the very same player instantly 'locked-up' when he was required to talk to an npc. He just never knew what to say. But he always insisted on playing social pcs, like bards.
Boy, was I glad when he no longer showed up for our games!