I get eg. 5 ping to Bitstamp I can tell you where they are in private if you want to know.
Bitstamp uses the Incapsula CDN which would probably explain your low ping times. Their DNS A records for bitstamp.net point to 149.126.72.187 and 149.126.77.187, which ARIN says are allocated to RIPE, and RIPE says they are assigned to Incapsula. Their CNAME for www also forwards to a Incapsula server. And I know from first hand experience that Incapsula will throttle connections if the bot is aggressive enough, and that they refuse to work bot developers to have their applications appropriately classified. Also interestingly although they try to imply they are an American company with the only address listed on their site being in San Francisco, all of their techs I spoke with are actually off-shored to Israel.
If you managed to find Bitstamps actual IPs which are behind the Incapsula CDN, I would be very much interested in knowing them, so feel free to send me a PM if you have them.
With that said, with Bitstamp you dont need to poll their API to maintain a copy of the order book, since they have a pusher API service for this. But other exchanges like Cryptsy (which also uses Incapsula) only offer push data for trades, not for the order book.
I do understand that there may be prices in books that the public including me do not see.
Rather than this being something the exchange is doing, I would probably place the blame with dark pool like services such as BTX Trader and other bots.
7 dollar spread does not prove anything. When I talk about profits it is the risk adjusted daily equivalent. To have arbitrage as a business model not as a gambling model, you need much more than 7 dollar spread.
Well that all depends on your risk models.
I catch spikes and the premise of my post was just that that no human can compete with me in that like crazyivan... I think we can agree on that.
Well it all depends on the type of arbitrage you're engaging in. If you're referring to inter-exchange intra-market, then yes I think a human technically could, depending on a variety of other factors which for obvious reasons wouldn't be appropriate to talk about here, especially if your risk models are as conservative as you imply they are in the previous quote.
And regarding crazyivan, I would probably have to agree with you, and that bitcoin-trader.biz link in his signature which advertises a arbitrage hedge fund reeks of being a Ponzi scheme.