Credit goes to Doctor Burger, but this seemed like a better range.

Classifieds:

http://backpack.tf/classifieds?item=Mutton Mann&quality=6&tradable=1&craftable=1&page=1

1=1.33

3=1.44

13=1.55

2=1.61

15=1.66

At the time of posting this.

1.33 Sold/Sellers:

http://www.tf2outpost.com/trade/23351927 (sold)

http://www.tf2outpost.com/trade/23332340

1.44 Sold/Sellers:

http://www.tf2outpost.com/trade/23338099 (sold)

http://www.tf2outpost.com/trade/23339444 -1 week (10% discount is around 1.44)

1.55 Sold/Sellers:

http://www.tf2outpost.com/trade/23390001 (sold)

http://www.tf2outpost.com/trade/23345855

http://www.tf2outpost.com/trade/23342516 (sold)

http://www.tf2outpost.com/trade/23277271

http://www.tf2outpost.com/trade/23374483 (sold)

http://www.tf2outpost.com/trade/23359672 (sold)

1.66 Sold:

http://www.tf2outpost.com/trade/23309711

http://www.tf2outpost.com/trade/22730990

http://www.tf2outpost.com/trade/23274307

Unsolds at 1.66:

http://www.tf2outpost.com/trade/23201095 2 weeks

http://www.tf2outpost.com/trade/23211951 2 weeks

http://www.tf2outpost.com/trade/22754809 1 month (poorly bumped)

http://www.tf2outpost.com/trade/23138432 - 2 weeks

http://www.tf2outpost.com/trade/23439511 - 2 days

http://www.tf2outpost.com/trade/23317329 - 1 week

http://www.tf2outpost.com/trade/23314278 - 1 week

http://www.tf2outpost.com/trade/23437959 - 2 days

http://www.tf2outpost.com/trade/22955561 - 1 month

http://www.tf2outpost.com/trade/23301906 - 1 week

http://www.tf2outpost.com/trade/23037211 - 3 weeks

Conclusion, 1.66 does sell, but not fast enough. Most of the other unsolds on OP are poorly bumped, new, or have something special about them.