A Senatorial Headscratcher

Here's something a little weird.

Survey USA aggregated and ranked the approval ratings of all 100 U.S. Senators, based on a variety of polling outfits.  You might expext (as I did) the top of the list to be populated by Senators from either strongly red or strongly blue states, where the Senator's political affiliation matched the state's electoral leaning.  The opposite turned out to be true.

7 of the 10 highest rated Senators represent off-color constituencies.  And 9 of the 10 lowest rated Senators hail from states matching their political stripes.

What gives?

                                                                                                                                                                                                                           

Rank	State	Senator	Party	Net Approval
1	ME	Snowe, Olympia	R	62%
2	ND	Conrad, Kent	D	56%
3	ND	Dorgan, Byron	D	54%
4	ME	Collins, Susan	R	50%
5	NY	Clinton, Hillary	D	50%
6	MT	Baucus, Max	D	49%
7	IL	Obama, Barack	D	48%
8	VT	Leahy, Patrick	D	46%
9	NM	Bingaman, Jeff	D	44%
10	SD	Johnson, Tim	D	44%
91	MN	Dayton, Mark	D	-1%
92	MA	Kerry, John	D	-2%
93	AZ	Kyl, Jon	R	-2%
94	KY	Bunning, Jim	R	-3%
95	FL	Martinez, Mel	R	-3%
96	NJ	Lautenberg, Frank	D	-5%
97	MT	Burns, Conrad	R	-15%
98	PA	Santorum, Rick	R	-21%
99	MO	Talent, Jim	R	-22%
100	OH	DeWine, Mike	R	-25%