I used my Wells Fargo Credit Card for a purchase in Madrid and it came up in USD. I did a quick calculation and got a decent exchange rate Euro/USD, so I did accept it and sign. When I got my card satement, Wells Fargo did not charge a currency conversion fee or anything. I paid the $185USD stated in the voucher!!

Comparing this purchase of $185USD to other purchases I made in Madrid, I ended up paying more for the purchases I got in Euros (thanks to the exchange rate + currency conversion fee) than for the $185USD purchase...