Running a Twilio application on my personal server was working fine until I moved it to DreamHost. At that point my XML was corrupt and closer inspection showed that double-quotations we're missing and the XML tags case-sensitivity was not preserved. Initially I examined both setups knowing that it must have been a configuration issue. I verified that short_tags were turned off. But the problem continued.
When setting up this specific domain on DreamHost, I had checked to use page speed optimization (Beta). Knowing about Google's page speed efforts, I assumed measured had been taken and this had an issue with XML rendering the issues I mentioned above. I turned off page speed optimization on that domain through the DreamHost control panel and gave it about 10 minutes for everything to actually switch over. I tested the result again and found it to be exactly as expected.