I have a Debian testing box with Xfce (no Gnome, no Nautilus). It has all gvfs-related stuff installed, including all backends and fuse interface. But any attempts to gvfs-mount anything (like sftp://... or smb://...) fail with error opening file: Operation not supported, and gigolo shows only 'unix device (file)' in the list of supported protocols.
My ~/.gvfs has rwx permissions, and I'm a member of fuse group; other fuse-related stuff works for me.
What do I do? Where to look?
This answer is based on the behavior I've seen in Arch Linux. Hopefully it is not much different from Debian's. (Also, because it was empirically determined, I am not sure if it is going to be actually a good one.)
It seems like you have to ensure that gvfsd and gvfs-fuse-daemon are running. Unfortunately, in my case starting them manually didn't have the desired effect. They started, but the problems persisted.
Since gvfs exports dbus services, it seems like gvfsd should be actually started by dbus. Are you using a display manager to log in or are you calling startx directly?
If you are calling startx (or using a display manager like SLiM), try to invoke your window manager/desktop environment with
exec dbus-launch --exit-with-session --sh-syntax startxfce4
in your $HOME/.xinitrc.
If you are using a display manager, check in its documentation what to do to customize how the window manager is called.
