What to ask, and why
Will this make me miss my next lease date?
Turnover treatments are usually planned between move-out and move-in. Give any provider both dates up front so treatment happens before paint and final cleaning.
Can I charge the old tenant for this?
Possibly, through the deposit, if your lease and Colorado's security-deposit rules support it. The invoice and dated move-out photos are your evidence; an attorney can tell you what holds up.
Will plaster walls ever stop smelling?
Plaster can hold residue, but surface treatment plus sealing before paint is usually effective.
Do I have to treat the whole building?
Not necessarily. Units are usually assessed individually; mention if odor seems to travel through shared chases.
Will the new tenant smell fragrance?
They shouldn't. Ask whether any fragrance will be added; the goal is a neutral-smelling unit.