Why didn't Yamcha lose his scars when he ate a Senzu Bean?

[nickzambuto]

We know that in canon, Yamcha has eaten at least one Senzu Bean. The earliest instance I can think of is when Gero put his hand through Yamcha's chest. If Senzu Beans heal all wounds, why didn't Yamcha's scars heal and fade away?

[VegettoEX]

Far be it from me to dish out accurate medical explanations, but I believe a scar technically already is "healed", so there's nothing beyond that a senzu would be able to do.

[Gyt Kaliba]

That'd be my best guess too. Maybe if he'd eaten a senzu bean as soon as the wounds were inflicted, but if they had time to heal over even slightly before he could get to one, then they're there to stay.

For a real world answer? Toriyama just thought it'd look neat on the character and that was that, no further thought needed.

[Darkprince410]

As VegettoEX commented, scars are, by definition, already healed. The reason it appears different than normal skin is how the fibers in the tissue are aligned, as normally it's in a basket weave sort of structure, while in scar tissue, the fibers run all along the same direction, but it is healed tissue (not as functionally sound as the original though), thus something that couldn't/wouldn't be repaired by a senzu.