I've been denied entry to D once, departing on a lunch run right after a Champion. The Champions was cleared through the D, the rest of us had to go around . . .
ATL has never cleared me into their Bravo, even when I've asked specifically for a T Route by number and been on an IFR flight plan. So now, I just hold my altitude (8000-10,000 msl), zoom the 430W in to about 25nm scale, and keep my wingtip just barely outside the little green line. This is even more fun VFR, they get to vector the big boys around me if I'm on the Approach side.
If they ignore my requests, I'll make my life as easy as possible and add the fewest extra miles to my trip. The typical detour adds almost 30 minutes to my typical "across Atlanta" flight, while putting me on the T Route designed exactly for doing what I want to do will save me time and them aggravation. But they never learn . . . .