You aren't going to find many unusuals for 12 keys, even ones as bad as this.

http://www.tf2outpost.com/trade/9958151 : Buyout - 14 Keys,

Offered a TS Bills + 2 Keys + 4.22 Ref. (Around/A little bit over 11 keys.) Rejected.

http://www.tf2outpost.com/trade/7376561: Offered 11 Keys, 11 Keys + Sweets, Black Bills + Kringle, Gold Bills + 2 Keys + Sweets,(Although this was 3 Months ago.) All Rejected.

Offered 13 Keys 2 months ago as well as 13 Keys + 2 Ref, 13 Keys was rejected, while 13 + 2 Ref was left open. Then was offered 14 keys for the Hard Counter and was rejected.

1 Month ago he was offered a painted bills + 4 Keys which was presumably rejected as he still owns the hat.

http://www.tf2outpost.com/trade/10092471 : Buyout - 14 Keys

Offered 12 keys + Poker Night at the Inventory + Cold killer + 1.11 Ref, was accepted but it's still in his backpack.

http://www.tf2outpost.com/trade/10109846 : Buyout - 14 Keys

Offered 12 keys + poker night 1 + Cold Killer + 1.11 Ref, Rejected.

Other Trades with no notable(if any) offers:

http://www.tf2outpost.com/trade/10131532

http://www.tf2outpost.com/trade/9934102

http://www.tf2outpost.com/trade/10154132 (Offered a bills, but I mean really...)