Thanks everyone for the feedback. Each ship had it own reasons for the styling.
The Hammerhead was build for the Maschinen Krieger starfighter contest on flickr. I created the large custom skull and number stickers to fit into that universe. If you check the image below, you will see the skull design I based it on. http://www.coolkits.de/kits/lunadiver.jpg
(the image size is too big to embed).
Since the Vic Viper design is from a video game universe (Gradius), I purposefully made the Guardian Angle look gaudy (not surprised by the eye-sore comment at all - It definitely is). It is also inspired by the Blue Angels, and wanted to have the apperance of a "show plane". Video game ships always seemed to have more weapon choices and upgrades than what you would think could fit onto them too.
The Banshee uses only stickers from Alien Conquest. It was for a FBTB contest, and they only allow using official LEGO parts.