Instruct: Classify the given Amazon review into positive or negative sentiment.
Query: !! SCAM: uses colour inks for black in duplex and grey in general

Hard to belief but true. Canon support confirmed this "issue": this printer (also next generation mx850) uses the colour ink catridges for printing in grey. Further it prints black in duplex mode with the colour catridges, too. If a customer wants to print in black he is right to expect that the big black ink is used. So, actually this is a SCAM from Canon to its customers. That makes the printer tremendously expensive.