Many agents begin with a lead program, their sphere of influence (SOI), or a combination of tactics, only to abandon them after 3-6 months.

Delay tactics, stalling, etc....But, the owner has a home Free and Clear!

Find a "proven successful" mentor that can guide you in relevant marketing strategies so you don't waste your money on old marketing tactics that don't work.

Quote from @Gustavo Delgado: just deduct from the deposit and keep the receipt This would be an interesting negotiation tactic to offer the tenant if they can't square up out of pocket before renewing.

Have you tried any other tactics?

I thought others might have some tactics they've used to bring a problem tenant into line and maybe they could share some of their secrets. 

Sellers, agents, wholesalers and investors are well aware of this tactic and will simply not reply or reply back with an “as is” offer especially if the property is getting a lot of interest.Buying is the easy part.

Your accountant will need to help you process through the long term tax planning ramifications of different tactics. 

I’ve literally had other agents who I know are good people suggest lead tactics and/or selling tactics that I think are kind of shady, but they are so deep in they genuinely don’t realize there’s anything wrong or unethical about it.

However, they talk about all these tactics and approaches (Being empathetic to the seller's needs, finding out the seller's true motivation to sell, presenting 2 offers) as if there is a direct dialogue occurring between the buyer and seller.