Passers-by saw him as a slimy slug

But, in fact,  Sam was a snail who'd had a bit of bad luck 

(I imagine Sam the shell-less snail playing an instrument on the footpath with his cap in front of him to receive donations. Next to him are a line of down-and-out slugs who look on their neighbour with rolled eyes and smirks. Passing posh snails with briefcases and top hats and lady snails wearing pearls sneer at him and possibly say something like 'disgusting slugs' in speech bubbles.)