Using the hyphen in "friendly-looking" is incorrect. The exception for hyphens in compound adjectives is when the first adjective ends in "ly." It should be "friendly looking couch."
Most "-ly" descriptors are adverbs, and it is indeed incorrect to compound "-ly" adverb-adjective combinations with a hyphen. (For example, "finely-chopped garlic" is incorrect). But adjectives that end in "-ly" can be hyphenated. ("Friendly," "elderly," "dastardly," "squirrelly," "burly," "lovely," "ghastly," "deadly," and so on).
These days writers often choose not to hyphenate them, as compound-hyphenation in general is dying out in contemporary usage. It often feels old-fashioned and fussy in informal writing. But there is no rule prohibiting the compound-hyphenation of adjectives with "-ly" endings.
That is so arbitrary. Your source and the OP's source are linguistically prescriptive. Prescriptivism is unscientific and it leads to endless spats between groups of people that think the way they learned to speak and write is somehow superior. A better approach is to look at the reality of how native speakers of a language use, pronounce, and write words (descriptivism) and agree that some uses are standard, and some are non-standard.
Here are some screenshots of collocation searches involving post-adjectival 'looking' from the excellent COCA...
'good':
http://s9.postimg.org/r4cok4spb/good_looking.png
'nice':
http://s9.postimg.org/kcm9ha3pr/nice_looking.png
Here's one for your author's example, "well known" (or "well-known"):
http://s9.postimg.org/64wksmr0v/well_known.png
Notice that the reality bears almost no resemblance to the prescriptive idea of what's correct and incorrect.
The "Friendly-looking" in "Friendly-looking couch" is an "adjective + participle" construction, which is hyphenated before the noun.
http://www.chicagomanualofstyle.org/16/images/ch07_tab01.pdf