It turns out that if the vocal majority of Twitter's users take offense to your willy-nilly tax avoidance then it might not be the smartest thing to crack on a hashtag and leave it unmoderated on your website. But of course Vodafone didn't really think this one through and went ahead with it, so at the time of writing this you would expect #mademesmile was a trending topic in the UK, but I hate to spoil you parade, it's in fact a worldwide trending topic (just under a promoted one, which doesn't count).
When ever you mention Vodafone and Tax Avoidance their PR team quite quickly pounce on you throwing their vaguely worded statement at you with the tag line "have a look here for further information", unfortunately this is about as helpful as First Great Western's train information system and we all know they need a little help with brand management too.
I think we all like to know, much like the Apprentice, who's going to be fired over this fiasco. Vodafone, you're not T-Mobile, people don't like you and trying to crowd-source is a bad idea. So keep to your boring old dry ideas like Bees that tie in with Freebees (HAHA ROFLCOPTER) and go die in a social media corner or until you stump up that £6bn.