I don't agree with the insinuation that what the Flipper (or any other wannabe flippers) does is either wrong or necessarily detrimental to other traders in the market.
It is true that his actions do have an effect on the market and so typically when he decides to go long (or finds himself with a long position due to sitting on bid and offer), he is able to move the odds in his favour that he makes money. However, there is obviously far more risk involved than German debt getting downgraded (when he is long) and a terrorist incident (when he is short). Presumably he is fully informed and prepared for scheduled data releases, but there are still plenty of unscheduled events or significant flows in the market that can cause him losses. Moreover, he is adding liquidity to the market, which would normally be welcomed by issuers, marketmakers, traders and investors.
But what I am more interested in than the morals of what he does is whether other traders can benefit.
If you are a mid or longer term trader, you will be unaffected (the Flipper does not move the market more than 1-2 basis points) and I doubt that he typically participates in larger movements.
If you are a short term trader/scalper/whatever you want to call it, your strategies certainly will be affected but you have new opportunities.
Whereas before you tried to make a tick or two out of the aggregate of a whole community of trading decisions, now you are faced with with a large additional player* who is probably doing something similar to you but in far larger size and considerably higher conviction. On the whole, you know that his initial trades will be supported by larger volumes if necessary. Therefore, if you can find a way of reading what he is doing and what his positions are, you can "piggy-back" him, significantly improving your odds of making the right call, and when it goes wrong you should be able to bail out quickly because there is always plenty of liquidity for your smaller size. It is obviously not easy to identify one person's actions in a large, anonymous market, but I consider it is easier to do this than it is to read an aggregate of many different market participants. A close look at the quote report of the various contracts can be very revealing.
Given that most allegations of market manipulation are unfounded, and the obvious resistance by Eurex to curtail the Flipper's activity, there is no point in complaining about his presence in various markets. Instead, try to identify exactly what he is doing and see if you can't adapt to improve on your original performance. I would be interested to hear what others think about this.
*I actually believe there is more than one flipper; only currently any large trade entries are attributed by many to Mr Rotter.