The sites that list supported printers are seldom up-to-date. Think how many manufacturers there are, constantly producing new items.
I think it's safe to assume that anything from HP is supported, and I believe the Samsung Unified Driver covers all their products. For the others, it's best to check before you buy: a search like "lexmark linux drivers" will obviously yield results. Searching this site for a specific printer will reveal if people are having a terrible time with it!
CUPS, of course, only acts as an intermediary in printing: it gets the a pdf file from the application, has it converted into a suitable format, and then passes it to the printer. The job of turning the application output into something suitable for your printer is managed by foomatic and ghostscript. A nice example of the classic Unix approach for divide and conquer.