In DUKE OF MT. DEER (or at least the 1984 TVB adaptation thereof), Seung-yee was quite shocked when she first encountered Russians. She had never seen or heard of Europeans before, and she thought they looked *really* strange and scary. Wai Siu Bo might also have had the same reaction, but he was slightly better prepared to meet the Russians because he had heard about gwailo while working in Emperor Kang Hsi's court.
By the time of the Qing Dynasty, there had been semiregular contact between China and Europe for several centuries already. Although most Chinese had still never seen a European (hence, Seung-yee's reaction), Europeans were not completely unknown in China by the DOMD era.
But what if a European were to show up much earlier in Jin Yong's timeline? Imagine if an Englishman showed up in DGSD, LOCH, ROCH, HSDS, or even SPW. Would the characters of those novels have found a Western European to be *really* strange (to the point that they might mistake him/her for a ghost or monster), or would a European not even be as strange as some of the people they encounter in wulin?