My personal goal is just net residual income of 3k by 35.

Of course that all depends on the purchase prices, rehab costs and residual income after expenses per annum.

Would you agree, I should do this only if I have extra residual income of $1400 month?

Once you get off, its hard to correct and you can see cracks and that adhesive strip really shows through the gaps.  

You can get vinyl floor which uses a pressure adhesive and the planks do not ship-lap or interlock; this allows each plank to be pulled-up/replaced without disassembling the entire floor.In (converted) houses, I tend towards hardwood (engineered or traditional), a good quality laminate, or ceramic/porcelain tiles (if the subfloor is stable enough).In {older}, stick-built multis, you are often compelled to use soft flooring options (carpet, vinyl, linoleum, cork), particularly in bedrooms and living rooms, due to sound transference.  

The glass doors also get a residue that is hard to get off. 

Residual is what its all about.

@Pavel Sakurets  With the supplies I used, it ended up being about 55.4 cents per letter sent - includes printed letter on yellow paper, printed envelope (self-adhesive), and stamp.

It's the residual from a successful mailing a year ago.

It's this sort of dumb thinking that gets politicians making more and more laws that make it difficult for the rest of us.There was a discussion on BP a few days ago about unenforcable clauses in contracts, and what you've just shown is one of them, and you are also demonstrating contract of adhesion incredibly well.