You can no longer for certain avoid low value trade good provinces, but there are still some regions who will almost certainly yield high value goods (the Caribbean, Brazil, Indonesia). This means that the strategy of avoiding low value provinces is no longer valid from In Nomine onwards. The province good is selected randomly from a group of goods that the province's region is able to produce. With the complete overhaul of the colonization system with the In Nomine expansion, colonial trade goods aren't fixed anymore and were 'discovered' randomly sometime after the colonization of a province started. In Nomine, Heir to the Throne & Divine Wind When colonizing, priority should be given to provinces producing high value goods (sugar, tobacco, cotton, coffee, chinaware, spices, tea, fur, gold), while the low value trade goods should be avoided initially (wool, grain, naval supplies) unless these provinces are of strategic value or have a high base tax value. In EU3 and Napoleon's Ambition, the trade goods of a potential colony are always fixed and known to the player upon discovery of the province.
1 Europa Universalis 3 and Napoleon's Ambition.