...is that Frodo is the first person to treat Gollum like a 'person' instead of
a 'creature' in hundreds of years. He asks Gollum's opinion, trusts
Gollum to lead them without being bound, and treats Gollum with a measure of
respect that Gollum readily responds to.
Basically, I think *Stinker* is responding to the possible threat of the use of
the Ring, while *Slinker* is responding to the kindness and respect Frodo
exhibits toward
him.
"I don't suffer from insanity...I enjoy every minute of it!"