Something you may want to try for a Minfernal. I got lucky and unlucky the same day, had camped and logged in for 2 weeks at random times. One day the second I logged there was a green paw, I was so excited I clicked to find I had level 1 pets equipped

and it was an uncommon to boot. The logout in battle had been fixed so I was screwed. I flew around and maybe 30-40 minutes later another appeared, It is poor or common I forget and a BB breed which I believe is not good so not sure if I should stone it and be done or look for better.
But the trick I do believe can make them spawn, you need help. The area is almost always crowded on my server and most of the toons are from other servers, so I am not sure if they are on my server or I am on someone elses, I wish they would just leave people on their own servers and nix this cross realm KaKa.
Ok OK, the trick is simple, have someone kill paws/other pets all around the zone while you keep watch for Minfernals, rats and moth and such will start to appear, just kill them and keep watch. It is best to do this early AM hours or when you can find few people there to be sure and see any that may spawn before someone else gets them. I have told 2 horde players now from other servers farming where ever we were to watch tightly, they had been trying for weeks, I went to killing stuff and both had a Minfernal within an hour and were so thankful, sadly neither offered to return the killing so I could try and upgrade mine but I did not care.
Good luck and let me know if it works.