This is an image of just litecoins hash rate for just 1 day 16th today... notice the 500GH gaps roughly. It is impossible to hide 850GH on the network, however its not impossible to turn them off and on strategically.
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Which part of "The only space for Scrypt.cc's hashrate to fit is in the 'Unknown' section" don't you understand?
The extra hashrate is already accounted for in known mining pools, mostly Chinese mining pools, by the way.