What is a reasonable gratuity for a tour. I am going on a guided tour of the Louvre and an audio tour of Musée D'Orsay. It doesn't make sense to me that they would be the same. What do you think fellow Paris lovers?
An audio tour generally means (correct me if I misunderstood your question) that a museum employee hands you audio earphones and gives a 10 second explanation of how to use them, then you walk around on your own. No tip needed for that.
Hopefully others who have taken a guided tour of the Louvre will advise you on your other question.
If it's an official Louvre tour given by a Louvre employee, tipping would be insulting because these employees are PhDs in art history for the most part and employees of the French government. We've been on some English-speaking tours with Paris Walks and Walks in Italy, but I don't remember if or how much we tipped.
France is not a tipping culture. If you sign up for a 'free tour' then the only pay these scabs get is through tips and it would be stealing their labor not to tip them -- I'd give 10 Euro -- but all these others examples are of people who are paid for their work. No tip.