I think the word would describe something that seems yucky (such as the combo of peanut butter cup ice cream and diet coke) but is actually quite delicious to the tastes of the person using the word.
Perhaps it could branch out to describe some people, such as if a friend knows her mate is yucky or slimy or sleazy but is still totally attracted, in which case the slimy boyfriend would (to that person) be yuckilicious.
I am, of course, totally making this up as I go along.