My last trip I gave a $10 tip to a waiter in a Spanish restaurant. I apologized that I didn't have euros. The guy smiled broadly and thanked me. If tip "culture" didn't exist in Europe, he would have thought of me as inappropriate and would have given the money back. Like if you try to give a tip to a firefighter, he'd give it back, because it's not appropriate.

Of course you can tip and nobody would refuse one. The difference is tipping is not expected by default and you get same service regardless of your tip. In contrast many years ago a waiter in a NYC restaurant made my then girlfriend crying when the waiter decided that the tip was not big enough. Is this great American service people here keep raving about?

He accepted it because he saw you as an American cash cow.

Obviously you will do as you please, but I wish tourists would try to get with the culture. As a European, one of many reasons I don't tip is that I don't want to encourage a class system where anyone who doesn't pay up is seen (and sees themselves) as stingy.

I have not been in a place in Europe where the tips would be rejected. However, universally they are not the norm or expected.

Also about the $10 - they would need to gather quite a few more dollar notes and spend time finding a cash exchange bureau. Else the note is just a memento of a weird American.

In some EU countries the tips have to be counted as salary and income (+social) tax paid, or even they have to be declared as revenue to the restaurant along with the VAT (19-25%) going straight to the state. Of course, when paid in cash - that rarely happens. The point is that the provision exists in the law (so the tips are not unheard of)