Girls, thanks for all the feedback. I apologize for not being clear with what I meant by "getting hung up by" SPs.
I "got hung up" by SP1 who told me to text her at 6pm to confirm our appointment for 7pm (which I did), did not reply to texts or calls throughout the hour from 6pm to 7pm (during which I called twice to double check on availability, both times getting vmail, while driving to the location as instructed), and only texted me back at precisely 7:05pm to say she could not access the incall location because some girlfriend was not answering her phone.
I "got hung up" by SP2 who emailed me at 11:57pm that she could see me at 12pm the next day (which I replied confirming that I could do the time suggested), and did not respond to emails/texts until 12:03pm (3 minutes pass the time we were supposed to meet).
Perhaps this is standard SP customer service practice? I hope not but it sure happened to me. Nothing more than bad luck I hope.