There are several reasons:1.I don’t need down-payment.2.This forces me to only do the extra-ordinary deals.

That's the same rate as your ordinary income, but its currently capped at 25%.

For those who use lines of credit, is that only for acts-of-god types of repairs or vacancies, or for ordinary capex, like a new roof?  

I own a business flipping vacant land properties so according to the irs I am a real estate dealer and my income is taxed as ordinary income which includes the full 15% self employment tax. 

You are going to pay tax at your ordinary income rate (depending on your income and if you are filing single or MFJ).

You pay ordinary income taxes, get really no tax benefits, pay social security tax and have to start over again after you sell.4.

@Brit FosheeI agree with you completely.  

B and C for me for the same reasons Brit mentioned.

PROPERTY MAINTENANCE: Except for ordinary wear and tear and Casualty Loss, Seller shall maintain the Property, including, but not limited to, lawn, shrubbery, and pool, in the condition existing as of Effective Date (“AS IS Maintenance Requirement”).

My lease states that tenants are responsible for all ordinary Landscaping which would include watering, mowing, and weeding. for larger tasks like pruning trees, I prefer to hire contractors that know what they're doing.as for pets, you can place restrictions on breed, size, or type.