They have different individual "shops" with different vendors and designs from said vendors. For example, pro-Obama stuff can be found at:
http://shop.cafepress.com/obamaThey show 112,000 Pro-Obama designs on 3,680,000 products and only 32,500 Anti-Obama designs available on 967,000 products. I think it's safe to say that the majority of Cafe Press clients don't believe in this kind of tripe.
The "Impeach" shirt may run afoul of their content guidelines though
http://www.cafepress.com/cp/info/help/index.aspx?page=cup.aspx"General Guidelines for Prohibited Content
* Content that may infringe on the rights of a third a party.
* Items that make inappropriate use of Nazi symbols and glamorize the actions of Hitler.
* Use of marks that signify hate towards another group of people.
* Hate and/or racist terms.
* Inappropriate content or nudity that is not artistic in nature.
* Content that exploits images or the likeness of minors.
* Obscene and vulgar comments and offensive remarks that harass, threaten, defame or abuse others such as F*** (Ethnic Group).
* Content that depicts violence, is obscene, abusive, fraudulent or threatening such as an image of a murder victim, morgue shots, promotion of suicide, etc.
* Content that glamorizes the use of "hard core" illegal substance and drugs such as a person injecting a vial of a substance in their body.
* Material that is generally offensive or in bad taste, as determined by CafePress.com."
One can report it here:
http://help.cafepress.com/hc/s-74058960/cmd/kbresource/kb-7158800860460397342/view_question!PAGETYPE?sq=offensive&sf=101113&sg=1&st=55338&documentid=155078&action=viewSome of the other anti-Obama shirts are pretty stupid and/or offensive. For example:
Somewhere in Kenya or Indonesia, a village is missing their idiot
Christian "Fish" biting an Obama logo)
You are entering a no-Obama zone. Mention his name and I'll drop you where you stand
Jesus Christ is my Savior - So Sorry Obama is yours
Silly Democrat, Read the Constitution
Barack
Hussein Obama - Enough Said
Change is also what Germany was looking for in 1932
Got AR-15?
USA - No Habla Espanol
Ignore The President - Listen to Rush - He's Right 98.8% of the Tim
Jindal / Palin '12
I suspect Cafe Press may start cracking the whip on the minority of right-wingers spewing shit like this. It doesn't seem to be the opinion of the majority of Cafe Press users though.