The meaning of scalar is something that holds a single value. A string (seen as an object) is a single value. An array, such as an array of characters of a string, is not a single value, because it has different "slots" for different pieces of information. A glob has fields, as you say yourself, so it is not a scalar, either.

In regard to LVALUE, it means something more specific than that.

perl -l
$s = '123456789';
$r = \substr $s, 0, 1;
print ref $r; $$r = "x";
print $s

LVALUE
x23456789
[download]

I understand what's going on, but I don't know this feature well enough to comment on its general use.