How to Google a question mark?

From Google FAQ:

With some exceptions, punctuation is ignored (that is, you can't search for @#$%^&*()=+[]\ and other special characters).

Following here:

Punctuation that is not ignored

• Punctuation in popular terms that have particular meanings, like [ C++] or [ C# ] (both are names of programming languages), are not ignored.
• The dollar sign ($) is used to indicate prices. [ nikon 400 ] and [ nikon $400 ] will give different results.
• The hyphen - is sometimes used as a signal that the two words around it are very strongly connected. (Unless there is no space after the - and a space before it, in which case it is a negative sign.)
• The underscore symbol _ is not ignored when it connects two words, e.g. [ quick_sort ].

So it seems that ? will be ignored by google no matter how you feed it to the search engine.

The only search engines that I have seen being aware of punctuation were code search engines.

The search index does not store everything. Though some special characters (like in C++) appear to be in the index, I doubt question marks (and common words) are in the search index. And hence you cannot search for it.

To get an idea of what seems to be in the search index, one can look at the help text in the grey box (below "This is Google's cache of superuser.com") when asking Google to highlight terms from the cache. Google silently refuses to highlight things that, I guess, are not in the index, even though they are in that cache. For Super User's cache:

• super user: These search terms are highlighted: super user
• lorem ipsum: These terms only appear in links pointing to this page: lorem ipsum
• ?: (silently ignored)
• more?: These search terms are highlighted: more (so: the question mark is silently ignored)
• c++: These terms only appear in links pointing to this page: c++

It even refuses to highlight common words, which (nowadays) are actually allowed in a search all by themselves, like "how":

• how: (silently ignored)
• how faq: These search terms are highlighted: faq (so: "how" is silently ignored)

I'm pretty sure Google strips all queries of question marks (?s( by design, regardless of whether they exist inside quotes or not. This is probably because the less "Google-aware" ask everything as a question, when they simply want to be searching for terms. Unfortunately, I do not believe there's any way of escaping the character.

The vast majority of the time, question marks are indeed irrelevant, though understandably in certain contexts, including programming, it may be useful to include them in a query. Suggest the idea to Google? I can't say much more really...