I've been noticing several uses of guardarci as a demonstrative pronoun:
Is there a reason or a rule to not use "guardare" in these cases?
This -ci particle just means “with it”, “in it” and the like. (It is not to be confused with the homonymous -ci meaning “to us”, as in Devi darci una risposta, “You have to give us an answer”).
In a sentence like Stavo per guardarci dentro, you are saying “I was about to look in it”. You might well say Stavo per guardare dentro, just like in English you might say something like “I was about to look inside”: in both cases you are not explicitly specifying dentro, or “inside” what, but often it will be clear from the context.
Analogously, if you have a sentence like Ho costruito un telescopio per guardarci il cielo (“I built a telescope to look at the sky with”), you might modify it in Ho costruito un telescopio per guardare il cielo (“I built a telescope to look at the sky”).
Notice that this -ci (just like the -ci meaning “to us”) can also be used by itself, rather than as a suffix: Ci guardo dentro (“I look in it”).
Guardarci le stelle / i film =~ "The act of looking at the stars / watching "the" movies for ourself" or "The act of looking at the stars / watching "the" movies in there"
Apologizes for the "for ourself" part, which is hard to translate (at least for me), but I think I've got pretty close with it: expanding its meaning a bit, "for ourself" should be intended as "in a way so that the purpose of the whole thing is just for us to enjoy it". Again, still not quite there, but to understand this meaning thoroughly try to consider also, e.g., "Mi mangio una mela" compared to "Mangio una mela".
I second Josh61 in stating that the first acceptation is probably dialectical; However that doesn't make it incorrect, it's perfect italian. It's just that, in my experience, I've never heard of it, e.g., being used in Tuscany but I've heard of it, e.g., being used in Puglia.
In any case, as remarked in the comments by DaG already, the first two probably miss a context regardless; in that case, the "-ci" particle could mean "for ourself" as much as it could mean "in there" ("in there" in the same way it does in the third one). As you may know the "-ci" particle is very tricky in italian and its meaning can vary within a wide range depending on the actual context; therefore adding some context to both we could make four correct sentences out of them, two with "-ci" actually meaning "for ourself" and two with "-ci" actually meaning "in there":
Andiamo a guardarci le stelle?
Andiamo a guardarci i film?
Cosa sei andato a fare nel giardino? - Sono andato a guardarci le stelle
Cosa sei andato a fare nella sala proiezioni? - Sono andato a guardarci i film
Answering the question itself: "Andiamo a guardarci le stelle / i film?" and "Cosa sei andato a fare nel giardino / nella sala proiezioni? - Sono andato a guardarci le stelle / i film" could be substituted with "Andiamo a guardare le stelle / i film?" and "Cosa sei andato a fare nel giardino / nella sala proiezioni? - Sono andato a guardare le stelle / i film" leaving the phrases grammatical, but in both cases part of the meaning would be lost (in the first case due to the reasons explained above and in the second case due to a missing implicit remark of "in there");
"Stavo per avvicinarmi e guardarci dentro, ma ho ricevuto un messaggio" could be substituted with "Stavo per avvicinarmi e guardare dentro, ma ho ricevuto un messaggio" as well but again, part of the meaning would be lost (again, due to a missing implicit remark of "in there")
1) They three phrases are all in perfect Italian and perfect Tuscan. I was born in San Miniato - between Pisa and Florence, from a Tuscan father and mother and I had four Tuscan grandparents. 2) "Guardarci i film" (considering the full sentence) could not mean "let's go and watch a movie" (movies, more precisely). That "ci" could only mean "in it" (say, a room) or "with it" (say, a projector) and not "for us" or "ourselves" or similar. 3) In the third case, "guardarci dentro" can only be "in it". 4) Only in the first phrase, the "ci" can relate to "us". In that case it reinforces the idea of "on our own", "alone", "for our pleasure", etc.
