When news broke yesterday that Twitter is to add location information to every tweet my heart sank.

Twitter’s Geoclocation API certainly has its benefits; it will usher in a new wave of spectacular apps showing what’s being tweeted about where, we’ll be able to search by location for relevant tweets and above all it will make our understanding of the Twitterverse all the more rich.

Put aside the lust for all this information though and we’re left with quite a few things that could go very wrong with all this data. Here are six reasons Twitter Geolocation is a really, really bad idea.

1. Crime

Remember the man who tweeted that he was out of town and came back to discover his house had been burgled? In the near future that could be you even if you don’t mention you’re away from home. The geocriminals of the future will simply monitor tweeting location patterns. Most of your tweets will be likely to be sent from in, or close to, your home. When you’re tweeting from out of area they’ll swoop in and swipe your stuff.

Yes, Twitter is making the Geolocation service opt-in, but if you try it out and forget to turn it off (which is likely to be all-too easy to do) or if you simply fail to understand the significance of the data, you’re in trouble. Insurance companies are already starting to advise not to “Tweet that trip”. When each tweet can have a geotag they might advise you don’t tweet at all, ever.

2. Celebrity slip-ups

Then there are celebrities – you might not care about them much but the fact some use Twitter brings a certain amount of kudos and glamour to the platform. Imagine if your favourite celebrities start accidentally giving away the location of their homes. Their privacy will be invaded by hoards of obsessives and before you know it the celebrities have jumped ship. Great for users who hate celebrities, not so great for Twitter.

3. Bad press

Reasons 1 and 2 will lead to a ton of bad-press, “Burgled by Twitter Crims” horror stories. Then there will be all the “Big Brother is following you” headlines as reactionary hacks accuse Twitter and third party app developers of building a massive people-tracking network. It will all be rubbish of course, but it won’t do much to encourage people to use Twitter.

4. Being ‘opt-in’ devalues the data you do get

Being an ‘opt-in’ service is definitely the right approach but it will certainly devalue any analysis of Twitter location data. “200 tweets a minute are coming in from the disaster zone” is much more useful that what we’ll get – “We’re seeing 4 tweets a minute from the disaster zone; there might be more but they’re not sharing their location”. Any maps, charts and graphs built from Twitter location data will be hugely under-populated as the majority of users won’t want to share their current co-ordinates.

5. Someone’s bound to write an app that gives fake data

“Want to be the first person to tweet from the South Pole? TweetLiar sends fake co-ordinates for your tweets“. That app doesn’t exist yet, but it can’t be far away. Whether it’s as a prank or as a deliberate attempt to trick people analysing Twitter data, it’s going to happen. When it does geolocation data will be devalued further.

6. You can’t filter who sees your location

I’m a big fan of Google Latitude which provides a similar service to the one Twitter is proposing. There’s a big difference with Latitude though, I can control how other users see my location on a user-by-user basis. Close friends can see where I am precisely, others see me on a city level and most people can’t see any location data at all for me. With Twitter’s API, that kind of micro-management isn’t possible and may put a lot of people off using it completely.

Conclusion

So, there you go; six reasons Twitter’s new API might fail. Now, I’m playing devil’s advocate a bit here – I like the idea of Twitter’s Geolocation API in theory and there’s no way to stop location services from developing, especially as they can be so useful in so many ways. It just seems that the way most people use Twitter is at odds with location sharing.

Still, people’s attitudes change over time – maybe in twenty years’ time we’ll all be constantly transmitting our locations as a matter of course and the idea of personal privacy will be dead forever. We’ve no way of knowing if that will happen but it will be an interesting ride finding out.