does a search engine exist where one can search the actual html source of a page..
 

rather than just the content on the page?
For example one could do a search for some random text in a comment tag and have it come up.

being that comment tags are not visible to browsers or spiders I'm guessing not.

but I have been proven wrong before ... anything is possible

comments are visible to both browser and spiders. just go somewhere and view source on it.
the question is does an engine exist that will let me search them..