"df" is inaccurate in Solaris 9 ???

After looking at several Solaris 9 servers, I have noticed that the df command is not accurate.  For example, a server with a 4 GB swap (as seen from the format command) and 4GB memory shows the following:
df -lk /tmp
filesystem              size           used            avail               capacity              mounted on
swap                     6.6G          5.1M            6.6G                 1%                    /tmp

This only thing that I can figure is that there are file handles that are causing the df command to look into real memory ???
Note that "top" is also inaccurate:
Memory: 4096M real, 3112M free, 397M swap in use, 6764M swap free
Even "swap -s" gives the funny 6.6G available number ????

The only thing that seems to really give swap utilization is "swap -l"
/dev/md/dsk/d0   85,1   16    8386736   8386640
Since swap -l in in 512k block, 1./2 of 8386736 is in the ball park of the actual partition size....

What is going on?  How can I accurately see what is happening with real memory and real /tmp ???