“How do I make cum taste better?” someone asked sex advice columnist Dan Savage.
“Cum” is not a word. We don’t have three-letter alternate spellings for other four-letter words that have double meanings. You wouldn’t write “I know this guy who sucks and he’s a mean dick, but he’s so fucking hot, I want to suk his dik.” The proper spelling of “come” works just fine too. But in answer to your question: Come is an acquired taste. No one likes Guinness the first time they drink it, right? But soon you’re happily knocking back pints of the stuff.
If you believe the Oxford English Dictionary, Savage is right: the OED doesn’t even acknowledge cum, listing only come, but I think in this case the dictionary hasn’t caught up with current usage. The contemporary dictionary at oxforddictionaries.com is a bit more yielding, listing cum as a variant spelling of the preferred come. In the other corner we have Urban Dictionary, which brings up more than 120 entries for cum that have pretty much the same definition.