I saw that dealers in las vegas are very rude, maybe they want to make themselves friends of the pitbosses by this behaviour? example: they expect more tips than anywhere, but even so they make dumb comments if one (ploppy or not) wins.
in West Europe: dealers expect a lot of tips, even if you loose they expect tips always when you have a blackjack. example: you have 2 chips of 100 Euros on the table, get a bj. the dealer gives you 2 chips of 100, one of 50, 3 of 10 Euros and 4 of 5 Euros, it is clear what (s)he wants. at least they do not bother much more with stupid comments, maybe they say: nice, you are very lucky. the wish is clear, but the comments are not so rude as from Las Vegas dealers/pitbosses.
Eastern Europe, Asian countries where i have been: they say twice thanks for any tip. they never ask indirectly for a tip. opposite: i have 3 chips with denomination 10, get bj, and dealer gives me a 50 chip and says: a 5 chip back please, more easy.
In sum I say: I do not want to exaggerate tips, but i can give something. about 1% of my winnings may be ok. my work is hard enough, too. and of course no tip if i have lost 5000 and recover it. and i will not give anything if dealer or other staff behaves rude. it is certainly rude if they tell indirectly: give more!