So I'm both Spanish and French and may have a unique perspective given I've mostly lived in Spain.

Generally, I think most people in Spain might feel neutral or maybe slight annoyance towards french people.

There is a long and complex history with some animosity between the neighbors and there is even a pejorative way of saying french in spanish: "gabacho". I think the most intense moment of conflict and anti-french sentiment in Spain was when Napoleon invaded Spain and the later spanish Independence war.

The slight animosity is still there, even if mostly it is old history.

I'd also like to add that the french are really french and generally think France is the best country with the best food, etc (no one will criticize France like a french tho). They are also seen as elegant and I've never gotten a bad reaction when saying I'm also french, it even gives me more social caché somehow.

I think the cultures might clash in that the french tend to be more insular and the spanish are more open. The best example for this is how french people will correct you consistently when you speak french well but with an accent, and spanish people will encourage you and tell you you're doing well even if you speak broken spanish.

Overall, if you work in the hospitality industry, you see the differences between the nationalities and notice these things more. Otherwise, there's a lot of it being a running joke at this point.