Spain has a rich easily recognizable flavor to its music that most everyone likes, at least in summer :-) Despacito has been the biggest hit globally for a decade and stll, most likely, Spain is going to send some nonsense or Swedish bubblegum to Lisbon 2018 Eurovision song contest - don't they ever learn?
Portugal won with a song that was very Portuguese and didn't try to please anyone or pow to any direction but the domestic market, if even that. And just because it didn't try to please anyone it pleased everyone. The same happened with Finland. When we sent something that was very Finnish and what Finns like, not giving a sh*t what the rest of Europe (and some Finns) think, we finally won with heavy rock and Lordi.
So, how about it Spain? Send something like superstar Pablo Alboran is doing, or the new flamenco king, the male Azucar Moreno in one: Demarco Flamenco. Spanish as can be with a lot of flamenco flavor to make it stand out. Pretty please?