pronouns - What's the difference between "these" and "those"?

First of all, I'm not a native English speaker, but in school I learned that these is used if referring to something near, and those is used when referring to something far away (temporally or locally). But now I'm sometimes watching English movies and notice sentences like "Have you seen those boots?" while the boots were only centimeters away. Is this just not correct, or have I learned the wrong rules?

Another question is, what if I'm referring to something abstract such as ideas or thoughts so that I can't say if they are far away or not. Should I use those or these?

Edit

So it can't be really wrong in any case if I use these respectively those?

Answer

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.