Kinda timely coincidence here, since I've been researching exactly this problem & solution lately.
Tracking in this industry is seriously flawed!
I don't see anything wrong with an opt-in cookie douche!
If the visitor decides my site/link is the one they want to signup under, or "finally signup under" in a case of needing to clear cookies.
Mysite/link = My player...period!
Its a shame we have to even think about clearing cookies etc. to correct a flawed system to get credit. It should be default protocol & the methods in place at the cardroom level to insure the above!
I'm w/Kaus also, bonus code or an "opt-in" cookie routine are no different IMHO.
my 2 pesos