I was ready to be pursuaded by odondon until I looked at your examples from Google. I think all three phrases are grammatical English. But the issue is very complicated. I would love to see some other comments on the thoughts I offer below.
I did a Google search on the terms "consider gerund" and found this grammar discussion at Wikipedia: http://en.wikipedia.org/wiki/Gerund
. Here is the relevant extract:
__________________________________[start quotation from Wiki]
Verb patterns with the gerund
Verbs that are normally followed by a gerund include admit, adore, anticipate, appreciate, avoid, can't stand, carry on, consider, contemplate, delay, deny, describe, detest, dislike, enjoy, escape, fancy, feel, finish, give up, hear, imagine, include, justify, keep (on), listen to, mention, mind, miss, notice, observe, perceive, postpone, practice, quit, recall, report, resent, resume, risk, see, sense, stop, suggest, tolerate, and watch.
Additionally, the prepositions "into" and "out of" can be followed by a gerund.
We postponed making any decision.
I simply adore reading what you write.
I detest going to the cinema.
We heard whispering.
His physician advised leaving home for a week.
They denied having avoided me. (= They denied that they had avoided me.)
He talked me into coming to the party.
They frightened her out of voicing her opinion.
______________________[end of quote from Wiki]
Note that the list of verbs here include "consider" but not "think." So odondon may just have substituted the wrong verb in trying to test the sentence's grammatical correctness.
Birgila's example is a little different from most of the Wiki examples in that the subject of the main clause is not the subject of the gerund. Without the change of subject, the gerund is definitely correct with "consider."
Now look at these examples:
I consider his going to the store unusual.
I consider his being rude unusual.
[I was tempted to write "I considered his peeing while seated unusual," but I will resist using that temptation.]
These are a grammatical sentences, but the subject of the gerund is in the genitive case, reflecting the use of the gerund as a noun phrase.
Some writers also use the accusative case here:
I consider him going to the store unusual.
I consider him being rude unusual.
These sound a little odd to my ear, but not really wrong. You will also find hits on Google with this case structure. But I think most speakers prefer the genitive case. I think one would have to consider accusative case non-standard in this construction.
The nominative case is clearly ungrammatical:
*I consider he going to the store unusual.
*I consider he being rude unusual.
The matter becomes more complicated, however, when the subject is "it."
If you Google "consider its being" you will get some hits, but not nearly as many as "consider it being." It appears that native speakers avoid the genitive case when the grammatical subject is "it" and prefer using the accusative case. (Of course, nominative case and accusative case are indistinguisable here.)
It is possible that the accusative case is also preferred when the subject of the gerund is proper noun:
I consider John being rude unusual.
I consider John's being rude unusual.
I think I would use accusative case in this sentence, but would find the genitive case acceptable.