You're confused because it's confusing.
I *think* for clothes for three and under it says something about 'aids in sleeping or feeding.' So bibs are covered. Sleepers, it would seem, would be covered. Pajamas.
I don't think a regular dress or baby overalls would be. But if you read the CPSC page, just look at the 'sports equipment' explanation (are these toys? the answer seems to be 'we decide that when we come to investigate'), it's easy to fry your brain.
Walter Olson, on this podcast:
http://craftsanity.com/?p=1625said Congress often 'outsources' bills, and he thinks the law was actually written by lawyers for one of the consumer groups, perhaps Public Citizen or Pirg, maybe another, and then Congress just put their names to it and passed it.