Tenant wont let me show rental unit

[Justin Case]

Luckily this is the first time I have ran into this.

Worst tenant is moving out after I gave a warning of a three day pay or vacate.
They paid the month in full and will not let me show the unit. I am not sure I want to show this unit since they are filthy.

I have a potential tenant who has drove past the place and saw several photos. I asked the other side of the duplex if I can show their side with a rent credit of $50 they said no.

All I can do is wait until the first of next month to show the unit.

Any tactics you advise I could use to show a serious potential tenant?

Thanks