You do suck.
But maybe not terminally.
The first comic you posted is a common first comic among people new to the site. They thing by switching the art around and making "woah, things are different in this panel" comments that comedy is somehow acheived. They you -- are horribly wrong.
Your second comic has potential, but I'd suggest a minor change to the middle panel:
/comics/not_Scyess/384009/
Your third comic is actually not bad. There's kind of too much going on, though; you could make it into two or three funny comics.
Number four is also pretty good. You need some more background on why a goth and a pirate are standing around the water cooler, though.
Once you learn the difference between nonsense and funny, you'll be in good shape. Keep trying.
