Take away the payment and you will see the enjoyment vanish
Ah, you missed my last minute edit!
Yes, I know that very few if any girls would be there if they weren't being paid, but some do seem to display genuine enjoyment while they are working, are able to orgasm, enjoy male company and attention.
The cynics might say that these are just very good actresses, but as long as they don't look sour or disinterested, it works for me.
The genuine Spanish girls I've met have been like this and it seems to really get them going if you can communicate in their lingo!