Is there something about a song that can be used to classify it as "a Tango"? There's different Tango styles (Finnish Tango music, for instance, is different from Argentinian) and there seem to be Tango elements in songs that wouldn't necessarily be classified as one.
Examples of non-classical Tangos include:
- "Little Drop Of Poison" by Tom Waits
- "Dos Gardenias", performed, for example, by Buena Vista Social Club
- "La Chanson Des Vieux Amants" by Jacques Brel
Songs that to me seem to have some Tango in it include:
- "It Takes More" by Ms. Dynamite
- "What Have I Done" by Anna Ternheim
I also have heard musicians refer to songs being "rearranged" as a Tango, and I wonder what that means.
Note that I don't mean "suitable for dancing Tango to". At Milongas (Tango dance events), the DJs sometimes play non-tango music, a good example being "Nothing Else Matters" by Metallica. As a Tango dancer, I can confirm that this song is quite "tangoable", but I'm pretty sure it's not actually part of the Tango genre. Also, there's famous and popular Tango pieces that are not very popular to dance to. Astor Piazzolla and Osvaldo Pugliese tend to fall into this category.
Wikipedia tells us that Tango is set in 2/4 or 4/8 time, but that is true for other genres, too. And while there's instruments that are traditionally used in Tango music (bandoneon and violin), there's plenty of songs that don't use them (there's many classic recordings from the 1930s with just guitar and vocals). Modern Electro-Tango music uses a lot of synthetic base drums, where traditional Argentinian Tango doesn't have percussion at all.
To more knowledgable people than me, it may be a helpful hint that there are particular genres that are "close" to Tango, in that composers and performers from those genres regularly cross over into Tango, or fuse the styles. Klezmer and Fado come to my mind, but Gothic / Metal musicians do tip their toes as well.