She evidently was sexually attractive, but "slick" means that she was clever at getting what she wanted. It means someone who is astute and persuasive but probably not honest:

"a slick person is clever and good at persuading people but probably not honest or sincere
a slick car salesman"
http://www.macmillandictionary.com/dictionary/american/slick

The basic idea of slick is "shiny", but lacking in depth: attractive only on the surface. But it also has this meaning of shrewd, plausible but dishonest.

"Two cents" is being used as a variant of "two-bit", meaning cheap, willing to stoop to any dishonest behaviour to get what you want. Two bits is literally two-eighths of a dollar, ie. a quarter, but it's an old expression for cheap, petty, contemptible:

"two-bit
Informal Costing or worth 25 cents: a two-bit cigar.
Slang Worth very little; petty or insignificant: a two-bit thief."
American Heritage Dictionary
http://education.yahoo.com/reference/dictionary/entry/two-bi...

""Two bits" or "two bit" continues in general use as a colloquial expression, primarily because of the song catchphrase "Shave and a Haircut, two bits." As an adjective, "two-bit" can be used to describe something cheap or unworthy."
http://en.wikipedia.org/wiki/Bit_(money)#United_States

It's very often applied to shyster lawyers, and a "two-bit slick" lawyer is one who will stoop to any kind of cunning trick. The speaker may also have had in mind the expression "a two-bit whore", a very low-grade prostitute.

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Note added at 1 day17 hrs (2013-03-02 23:35:38 GMT)
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The interesting reference posted by airmailrpl suggests another angle which had escaped me: "two-bit" may also carries the implication that her slickness was limited; she was clever enough to catch the country boy Ali, but no genius: cheap or insignificant, in the sense of not really being very competent.