In the 'Have you seen those boots?' example, if meant as an exclamation, there is also a sense of distancing oneself. That is to say if it was meant to imply "Have you seen those boots, they are fantastic/awful", one is indicating the boots are not yours, but belonging to someone else, and thus conceptually distant from you.
If the question is taken to mean "Where are the boots?" then their distance is unknown, and thus also conceptually distant.
In summary, I would use 'those' when something is either physically or conceptually distant, and 'these' when they are near to me, either in proximity, or my emotional sentiment toward them. That's the best way I can frame it logically, anyway.
I agree with you: it should be those, because the participial phrase that follows it (sold in stores) is of the defining type, and defining phrases are normally not combined with personal pronouns. They can be combined with personal pronouns, but I suspect unusual circumstances are required for that; at least in this case it sounds off to me.
Best Answer
These, those and them may all be used as objects of a sentence or a preposition.
Said when no books are present:
Said while pointing toward a flock of geese:
Said while holding a handful of diamonds.
You can also use two of the three as modifiers for nouns:
But it is ungrammatical to say