Just passing along our experiences to date, partuculary with BCG, to help others perhaps identify relative to their own experiences... Note that in addition to this foum, there is a huge amount of "dialogue" on BCC in the WebCafe's archives, which are easily seachable by keyword, but for which you need to register separately...
My spouse has TCC(Ta), high grade,---since 6/2005 she has had 2 TURBs, then 1 BCG course( 6 mo ago), a recurrence, another TURB, and now has started a second course of BCG, 6 months after the first course, this time with w/ interferon. Curiously, she is getting full strength BCG, and this from those people involved in the original O'Donnell work in BOS. (also see sites on the Web Cafe relative to O'donnell's work, studies, etc). They tell us that they only reduce the strength if you experienced adverse reactions previously. We had not. So myth no 1, I guess, would be - they don't always reduce the strength. We were also told they feel that interferon boosts BCG "potency" by another 40%.
Another "myth" we've had diminished - It is not necessary to roll around for two hours after BCG instillation. That once was the wisdom, but experience hasn't demonstrated any need for this - probably because the bladder pretty much shapes (shrinks) around what's in it so that it gets "bathed" pretty thoroughly.
We were also told that BCG loses it's toxicity (and value) after 2 hours. [mixing has to be timed carefully to dovetail with one's visit]. There have been arguments in the past relative to holding BCG "as long as possible." But apparently that has no value.
Everyone wants to be super careful about exposing ones partner and others following instillation, but apparently the real danger is only for a short while (hours) and the only two cases of TB infection our people knew of, had to do with medical professionals somehow being exposed to the BCG while virile, and probably thru inhalation of "fumes." One should still clean toilets well with bleach, but probably not for days the way we did the first round! And conservatively, the intercourse recommendations should be followed, but frankly, some seem unconvinced of the validity of such long running precautions.
Another item that has come to light this go around, for us: It is ok (normal?) to experience light bleeding and even passing tissue following instillation (- remember, I'm talking BCG + interferon; not sure if this applies to BCG alone). And we are experiencing this after this first instillation...But if more than a mild fever occurs, then there is probably an infection involved, and one should take immediate action (notify Doc).