Questions are sometimes edited for clarity. That's in the TOS. Sometimes our questions may be perfectly clear to us, but not to everyone else. The editing is not to make us "look like idiots;" rather, it is intended to spare us that fate.
Most websites edit submitted questions so they are more readable. These same websites may also edit otherwise unanswerable questions into relevant or interesting ones that their audience would enjoy. Spelling and grammatical mistakes are most certainly edited by the editorial staff. They may have deemed your question poorly written.
Yes, it happens often. Sometimes they will change the text of a question, for whatever reason, until the question barely resembles the original query. Don't use them.
