Barry wrote:

In what situations would you decide to track the traffic? I'm curious
because one very clear night I didn't feel like bothering with Phila.
Approach and just overflew the Philadelphia Class B VFR at 7500 enroute to
Atlantic City. When I called ACY Approach, they told me that Phila. wanted
to talk to me. I called after landing, and Phila. said they showed me below
7000 for part of the time, thus in their Class B without a clearance. I
assured them I was at 7500 the whole time, and agreed to get the Mode C
checked (it was due the next month anyway). Is ATC more likely to pursue a
possible Class B violation than a rogue IMC?

Yes. In most cases ATC does not know an aircraft is illegally IFR
because we don't know what the weather is. I have seen ZLC call a
couple times because they watched traffic for over a thousand miles.
One was a Malibu that busted LAX's class B and landed here at BIL.
Another aircraft busted Denver's class B and came here. Both times we
gave them a phone number supplied by ZLC. Don't know what happened
after that.