Bots don't necessarily make the market any less efficient though. Albeit a bit of a pain to easily analyze whats going on with all the random transactions.
True enough but it does tend to create a lot of bloat
Just a bunch of the same order at tiny amounts filling the orderbook and what not
I've played with a micro roll bot in php; basically it makes orders on both sides looking for small profits per trade. It's not good when the market is moving too quickly, but does well when there's a trend with less extreme fluctuations.