These are some things I consider when trying to determine if new growth indicates RRD infection:
1) Try and picture it in black-and-white -- many (but not all) roses have red new growth, but if it otherwise looks normal beyond color, that's not RRD. If, however, the questionable new growth was the same color as older growth and would still look strange, then it may be RRD -- or herbicide damage.
2) Look at the quality rather than the quantity of growth -- an abnormal amount of normal growth does not indicate RRD, but rather may result from recent heavy rains and/or feeding. The candelabra shoot in the first post would fall under this -- leaves individually look OK, despite the surprising vigor of the new shoot.
3) Some herbicides can cause similar-looking damage as RRD does, but again there's a difference. Herbicide damage will look abnormal in its parts and stunted overall, whereas RRD will look abnormal in its parts and vigorous overall. Again, differentiate this from normal in its parts and vigorous overall, as seen in the first post here.
:-)
~Christopher
