agreed that sweet is the default, unles hot is specified.
i like my hot sausage hot, and my sweet with extra fennel seeds.
if you want your hot sausage hotter, roll in powdered cayenne before browning or grilling.
for the extra fennel seeds, there's not much you can do unless you want to be a nutcase and use a chopstick to push them in the open ends, or break it open and add to a patty or crumble. don't push them through the skin or all of the juices will leak out.
A true lover of nature does not despair now that his mistress has turned a colder cheek.