If I were to write the pairing again - and I'd like to, someday, I'd use Giles' natural chivalry and good manners as a way to break through that barrier and have him perturbed and mildly resentful of the way Xander continually puts Anya down in front of people. I'd write about a really normal day in the shop and have them get closer and closer as the day progressed (or maybe a week...). I'd have Giles just take Anya off Xander because he didn't think Xander deserved her.

Or something. Heh.

But the Xander seeing smoke where there is no fire would be funny; or possibly...ooh, getting all sorts of bunnies... :-)