Maybe if you're trying out for a part in a stag film. Or if you want to look like Ivana Trump.
The trouble is, lip liner stays where it is pretty well, and lip gloss slips off in an hour or two, so there you are with clown lips. Maybe if the liner is very light, you could get away with it, but why bother? The purpose of lip gloss is sheer color; you don't need a liner for that.
