Why is soda considered bad for your teeth, particularly if you don't brush regularly?

Because soda contains a lot of sugar which will then ruin the tooth's enamel if you don't brush regularly 

When the person is unconscious, using oxygen, confused or disoriented, has facial trauma, is likely to have a seizure, is younger than 6 years old, has sores, redness, swelling, or pain in the mouth. i hope this .

Answer in 2009 barack obama signed into law the family smoking prevention and tobacco control act, the new law (h.r.   1256) represents the most sweeping action taken to date to reduce what remains the leading preventable cause of death in the united states;