my $spooler = `lpstat -r`;
if ( $spooler = "scheduler is not running" )
You're assigning to $spooler in your conditional statement (not just the backtick statement). You really should be comparing, or pattern-matching.
if ( $spooler eq "scheduler is not running" ) ...
if ( index($spooler, "scheduler is not running") >= 0 ) ...
if ( $spooler =~ /scheduler is not running/ ) ...
Given that this is output from some other tool, I would guess that the last of those alternatives is the most useful.
Update: After re-reading your question as posed, I guess I'll state what I thought was obvious-- I rarely want to assign (use the = operator) in a conditional statement. To compare numbers, you don't assign, you check for equality with the == operator. To compare strings, you don't assign, you check for equality with the eq operator. Also, the command output captured with backticks contains ALL of the standard output, newlines and all, so if your scheduler command really does JUST print "scheduler is not running", it STILL likely won't match exactly with the eq operator.
[ e d @ h a l l e y . c c ]