Hi Marcos,
you may want to read this:
hxxp://forums.malwarebytes.org/index.php?showtopic=128290
"... but as far as I know, we've [ MBAM ] never detected Ask. Ask is pretty much on par with Google and MSN/MS Bing as far as toolbars go. They always have an opt-out option in software installers and don't really do much other than show you search results from their search engine and gather statistical data (which all search engines do anyway, even if not using their toolbar as that's how they rank results and gauge the popularity of links/websites and handle their 'targeted' adverts)."
Is not like " other vendors simply don't focus on PUA " but rather they do not want to have an unnecessary detection; I simply cannot understand why, if nobody else on AV industry is detecting Ask! as PUA , ESET would continue to do it!