In my life time City have signed some garbage, so this is too easy or maybe too difficult to call.
We have had a lot of players who didn't justify their wages, their fee or the hype, they could all be considered, but we have signed some truly woeful players that score high on all three.
My stand out top three were not the biggest signings, or on the highest wages, but were so bad for the club it actually hurt...
1, Danny Mills, this man had a truly cancerous effect on the club. Drained us for wages for years and was and continue to be an utter knob head.
2. Replacing Coton with Immell. Do I need to say more.
3. Joint. Samaras and Bradbury. While Samaras was not the worst player, although he was pretty bad his fee at the time was so far out of reach, so unrealistic and unnecessary he could have bankrupted us. I felt sorry for the lad, he was played out of position too often, and he was expected to be the next Shearer thanks to the fee Pearce paid for him.
Bradbury for very much the same reason, too expensive at the wrong time. The fact that he couldn't hit a barn door with a banjo didn't help...
Those saying names like Robinho (our league top scorer & reason we signed many more talented players), Balotelli are simply insane or attention seeking!