Trademarks: Can You Parody Logos Without Licensing Them

i understand that small night markets and street markets in obscure places in asia can get away with this but i am curious how mainstream clothing companies and very prominent shops online get away with things like this?

My first question 1.) is there some kind of creative freedom clause that allows small companies to use other people's logos as long as you dont try to pass it off as an authentic piece?

for example this is from Obey a very big company with a huge following

http://i46.tinypic.com/mtq87s.png

or this one from Crooks & Castles

http://i47.tinypic.com/bga4gh.jpg

its obvious they are going for Gucci's signature color scheme. does Gucci have any control over that?

and how about these 2 pieces which are both from very popular clothing companies which prominently feature the chanel logo
again maybe considered a satirical piece titled "F*cked"

http://i48.tinypic.com/nc7pi.png

& the YSL logo incorporating it into a 'satirical' design "You Seem Lost"

http://i46.tinypic.com/2mxqzyx.jpg

i know there is some sort of legal loophole regarding parodies and satire which the above seems to be an example of but anyone know the specifics?

My 2nd question: how do toy companies get away with using someones likeness? does this also fall under the satire loophole?

for example this item

http://ecx.images-amazon.com/images/...500_AA300_.jpg

which clearly uses sarah palins name and image to sell their item. sarah palin doesnt have to "ok" this item?

or how about when authors and publishers write a book about her using her image likeness and her life story to sell a book. how is that even legal without her giving the okay?

http://photo.goodreads.com/books/132...2l/9537345.jpg