They are very variable. I lived with some Italian guys and often had a houseful of Italians and used to spend a lot of time in the restaurant they worked in and the accents varied widely.
I was taught Italian mainly by an Irishman and when I was in Italy and around the guys I lived with and their friends some were far more understandable than others, same as anywhere really.
Media can have a significant influence too, don't underestimate how much English speaking media there is in other countries, TV, film, music etc... Films and TV can also be subtitled rather than dubbed and much of it is American. I noticed this a lot when I was in Romania.
When I worked in France, The A Team and Walker the Texas Ranger were on every weekday evening and there was a lot of music with English in it, even sung by French and other foreign groups.
A friend of mine is French and was in Paris not that long ago and had a waiter keep speaking English to her as he thought she was! She speaks fantastic English but still has a very strong French accent.
Some people are also very good mimics though it is easier with some languages than others. I remember chatting to some Swiss guys in German once and they were amazed I didn't have an accent. Same with Welsh, I was nowhere near fluent but the my understanding and the bit I could speak would lead to problems with people thinking I was fluent. I pick up accents quite quickly but I did study only languages for years so was switching between a number of them day in and out so kind of came with the territory.
I see it a lot with people in city jobs too where they have learnt to hide their original more local accent as they think it makes them sound more professional.