They might also enjoy knowing that their security deposit will most likely not be coming back to them because removing urine odors generally requires steam cleaning and that is expensive.  

The only truly effective way to remove an odor is to remove the source, be it pad, drywall, or subfloor.

The rodents are are territorial and are leaving their odors of familiarity and do return.They put in a sonic anti rodent contoler in the engine, sprayed strong mint, chili spray, mothballs, set traps To no avail.A landlords lackadaisical attitude can cost you a good tenant with lots of repairs and damage.

You can send someone in now but there's no way to look behind all their stuff and get a real scope of damages, odors, etc.

It was not too bad (dirty carpet and sticky floors) but the smell of trash and body odor was fairly repulsive.

Posted 30-Day Notice to Vacates on June 25th (I actually gave them until July 31st), along with an intro letter on how/who to pay July's rent to and that they cannot use their security deposit for last month's rent.There were grumblings from two of the units along the lines of "oh, bummer, I wish I hadn't just paid rent." 

The quality of the tenant base, historic appreciation, job growth, etc is just too good to be worried about grumblings of rent control. 

If I were you, I would replace any fabric, ie. carpet, I would pay a cleaning company a couple hundred buck to do a deep clean, change any HVAC filters, then I would go to Home Depot and buy an odor bomb or two.

This behavior is in violation of the lease agreement which you signed on (date of lease) which states in section 12: “Disorderly Conduct—Tenant agrees not to permit or suffer any disorderly conduct, noise, vibration, odors, or other nuisance whatsoever about the property and further shall not annoy, disturb, or harass neighbors or other residents of the community and to use no machinery or other apparatus which would damage the property or disturb neighbors or other residents in the community.”

If you're not going to allow pets, insist the building be pet-free and since there are multiple pets in it now, insist that it be delivered clean of all pet odors/materials.