For me, music is at least half of the dance. If I don't like the music, I am really not going to enjoy the dance. I know it's subjective but my main criteria is that:
The beat and tempo is appropriate for the dance.
The MOOD is also appropriate.
Now, I'm not asking for Espani Cani for every Paso (oh go on then

) but you don't need to stick to that. There is a wealth of traditional Spanish music that has never been used. The same applies for the Charleston, yes I like Cabaret, but it is not strictly speaking a Charleston song. What about the many fantastic songs that were written in that era, the 20s, that have hardly been touched? Laila and Anton's was brilliant to Yes Sir, That's My Baby, and there are so many more to use. Chelsee's Paso to Malaguena was spine tinglingly wonderful and nobody can convince me that it would have been as equally effective had it been to a boringly repetitive rock number.
Now, some pop tracks can work IF they are as said, the right beat and mood. One I can think of is Darren and Lilia's Paso to Don't Let Me Be Misunderstood which has a definite Spanish flamenco beat and had the right mood in the lyrics. Another I liked was last year with Victoria and Brendan's Tango to White Wedding. I cannot remember the artist, but the mood and beat were great and contributed to it making it her best dance. Let's Get Loud is a great cha cha, and there have been lots of others.
So I am not averse to pop tracks at all IF they are carefully chosen. I do have an aversion to Queen which has been done to death on SCD, and usually not well. But Patrick and Anya's AS would not for me have had that impact had it been to a generic pop tune, the fact is, songs from that era, stretching from the 20s to the 50s, were designed to be DANCED to, (and performed to) when many pop tracks you really really cannot with the best will in the world, ballroom dance to. Because they are not written with that in mind. It surely cannot help the celeb either, if they are struggling with a dance to try and dance it to a totally inappropriate song. If they get criticised for timing, it may not always be their fault!
What frustrates and saddens me is that there is a wealth of wonderful music which SCD would be the perfect vehicle for, to get to a wider audience, and it is so little played on the radio, excepting a few specialist programmes.