I bought my RAV4 used, and the interior and HVAC system smelled really bad. I cleaned and shampooed the interior, replaced the floor mats, sprayed Lysol in the fresh-air intake, replaced the cabin air filter, odor-eliminator-bombed the interior, and used a can of odor-eliminator through the drain tube to kill and disinfect the A/C evaporator. Still kind of smells a little. The interesting thing is that even after running the A/C on full-blast, for over 30 minutes, I still did not see a single drop of condensation drip out of that drain tube. I think I'm going to unplug the tube and see if it is clogged. My Tesla Model S seems to produce a huge amount of condensation on the floor of my garage in that same amount of time.
BTW, it's easy to find the drain tube if you look in the passenger-side foot-well, pull-off the furthest panel (next to center console), and pull-back the carpet. You will see a tube that runs from the HVAC housing to the firewall.