Guys new to S. America often struggle with the Spanish accents and the Spanish names. It gets better.
Female Japanese controllers? Probably the hardest to understand. Accent and femlae voice, for some unknown reason, make it tough to understand. Coworkers usually agree.
Love standard RT, until it's stupid. Freq change - 127.025. "One two seven decimal zero two five."
Flip the radio and it goes 127.010, 127.025, 127.030. Why bother with the 'five" when saying ".025"? It's just another number to remember when there is no .020, .023, .027, etc, etc.
And oh the horrors, 'oh' instead of 'zero'. Or 'point' instead of 'decimal'. Yeah(that's U.S. for yes), I use standard RT except for the occasional "FL 21.3 climbing to FL330". Dem Brits, 'em some smart fellas and they git it. Fast learners. Proud of 'em.