In Robin #113, he goes undercover as a hitchhiker named Gary Glanz. Like Alvin, Gary has scruffy facial hair (in a different arrangement, and also bushy eyebrows). The scruff turns out to be fake - if I recall, he rips it off when he changes into his Robin duds.
I won't be able to get to a scanner until tomorrow, unfortunately. If no one beats me to it, I'll share then.