There are over 650 service stations in Baja Norte, the list represents around 10%. If you go to the
http://webapps.profeco.gob.mx/verificacion/gasolina/, you can enter the station number and it will show if any complaints have been filed and what the resolution was.
I took some of the stations from the list and a couple came up with a "yellow" light. The comment section says the station was fined for refusing the inspection. Maybe the despachadores were told not to allow inspections unless the station manager was there. Also, once the inspection was completed, the fine could have been canceled.
My advice is to check the website above, take a measurement if you use a particular Pemex with frequency, file a complaint if necessary with both
Pemex Website as well as with Profeco.
I have never seen an inspector at a Pemex or at a station in the U.S. (someone will come along soon and say they see them all the time in the U.S.). In the U.S. it is state driven and the number of inspections depends on the budget for that department. Some pumps get an inspection in a particular state maybe once every six months to a year and some go even longer.
I think it is difficult to say whether a pump is not working properly (not always rigged, can also be faulty, worn out, replacement needed). You really need a system of measures. If not, looking at your gas gauge and the gas pump, taking into account currency conversion, it is guessing.