CDs with Highest Third Party Performances

[HAnnA MArin County]

Below, I've taken the results from three of the "major" third parties' best performances in the past two election cycles. Does anyone have any explanations as to why these third party/Independent candidates ran so well in these congressional districts? Is there a history of voters giving such high margins to third-party candidates in these districts? 

Libertarian Party
2008: CA-26
David Dreier (R) 52.64%
Russ Warner (D) 40.44%
Ted Brown (L) 06.92%

2010: CA-28
Howard Berman (D) 69.54%
Merlin Froyd (R) 22.42%
Carlos A. Rodriguez (L) 08.04%

Green Party
2008: CA-01
Mike Thompson (D) 68.10%
Zane Starkewolf (R) 23.36%
Carol Wolman (G) 08.54%

2010: IL-04
Luis Gutierrez (D) 77.36%
Israel Vasquez (R) 14.32%
Richard J. Burns (G) 08.32%

Constitution Party
2008: UT-03
Jason Chaffetz (R) 65.61%
Bennion L. Spencer (D) 28.28%
Jim Noolander (C) 06.11%

2010: OH-18
Bob Gibbs (R) 53.86%
Zack Space (D) 40.49%
Lindsey Sutton (C) 05.64%

Independents
2008: OH-02
Jean Schmidt (R) 44.83%
Victoria Wulsin (D) 37.46%
David Krikorian (I) 17.70%

2010: OH-17
Tim Ryan (D) 53.89%
Jim Graham (R) 30.08%
James Traficant (I) 16.03%