Out of curiosity, what is the correct method for checking if I have a parasitic draw on the battery?
Do I check ohms by disconnecting the negative pole on the battery and measuring positive to ground?
No. Parasitic draw is tested using a low-amps ammeter. Generally, this would be the ammeter section of a multimeter, typically rated for ~10 amps DC, and protected by a very expensive and uncommon fuse internal to the multimeter. With the ammeter set to read 10 amps maximum, test leads in the proper sockets of the ammeter (generally the red lead is swapped from the usual socket to the ammeter socket, the black lead staying in the "Common" socket) one of the battery cables is disconnected from it's terminal on the battery. (Doors shut, ignition and electrical accessories such as lights turned off) Can be the positive or the negative cable. If positive, the red lead is connected to the battery + terminal, the negative lead connected to the loose end of the + battery cable. The meter needs to be watched for awhile--long enough for the computer and other electrical drains to "go to sleep"--perhaps one minute, usually less. The reading is taken then.
Fancier, more "user friendly" ammeters have a clamp-on inductive lead. No need to disconnect the battery, the lead is merely clamped around the cable. Again, doors shut, ignition and accessories turned off, and enough time allotted for the computer to go to sleep.
If in doubt, follow the directions given by the meter manufacturer.
Older cars with mechanical clocks driven by an electric motor would "pulse" current draw--the motor would draw power for a second or two, which wound the main spring in the clock. Then the draw would end. The clock would run off the mainspring until the mainspring wound-down--and then the motor would wind the mainspring again.
Similarly, modern cars may leave "courtesy" lighting on for several seconds--maybe minutes--after you shut everything off. This power drain has to be allowed to turn off before your meter reading is valid.
Lower amperage draw is better. Old cars with no computer or electronic clocks could have "ZERO" amperage draw. Modern cars need some power for "keep-alive" memory in various computer modules, or other electronic devices. So you'd need to confirm the allowed drain with factory specs--but certainly less than one amp, usually less than half-an-amp, and perhaps less than 1/10 amp.