It's been shown before in multiple episodes that only direct sunlight will cause a vampire to burst into flames. Yet, strangely, when Buffy and Faith burst in on the vampires' nest, the one vampire's clothed (and therefore shadowed) arm bursts into flames, yet his fully exposed hand is fine.
EditS 7 : Ep 22
Aired 5/20/03
S 7 : Ep 21
Aired 5/13/03
S 7 : Ep 20
Aired 5/6/03
S 7 : Ep 19
Aired 4/29/03
User Score: 3304
User Score: 1138
User Score: 1531
User Score: 1370
User Score: 588
User Score: 498
User Score: 379
User Score: 217
User Score: 197
User Score: 155