for my $dir (glob "*") {
    # for a brief moment, $dir might not hold a directory's name
    #      ^^^^ that's ok -- you just check if $dir is okey for you: 
    next unless -d $dir; 
    ...
}



for my $dir (glob "*") {
    -d $dir or next;     # put "-d" first, because it is more importan
+t than "next"
    $dir =~ /photos|thumbs/ or next;  
    ...
    ... 
    ...
    ... bla bla $dir
    ...
    ... bla bla  for (...) { 
    ...               bla bla $_ and $_ ... 
    ...               and $dir 
    ... }
    ...
    ...  ... $dir... 
    ...  ... # long loop body --  it is important to use "$dir" variab
+le ... 
    ... 
}



Short processing: 

for (glob "*") {
    -d or next;                # "or next" -- fall back less important
+ then "-d"
    /photos|thumbs/ or next;  
    do_something
}



Better written like this, data flow from bottom to up: 

do_someting with $_ for               # finally feed good dirs to "do 
+something" 
     sort                             # third step 
     grep { -d && /photos|thumbs/ }   # second step 
     glob "*";                        # first step
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