Walking the property before closing is definitely worth the cost to avoid bigger headaches later, especially with flipped homes where the quality of renovations can vary.

In each market I operate in I have someone available for showings this person is usually my runner who is responsible for quality control and restocking inventory but I've also used a cleaner for this.

So, 400k - 500k sounds like lots of money but if you wanna operate in the 300k+ entry point it get can swallowed up quick.One strategy I'd try is to be a buyer at the auctions, win a bid on a good house, close on it in cash (you should be a great deal under market value) and then get into a delayed purchase bridge loan product which will cash you out a certain percentage of the purchase and supply the rehab funds. 

IE at the time if you built on all the hundreds of thousands of lots there you would have perpetual grid lock not to mention water quality etc etc.

You'll see rate improvements at 25% and 30% down for most loan products.

If an operator is not responding to you adequately - in timing or quality - prior to you wiring them $50,000, you have to ask yourself how will they respond after they already have your money? 

You could use a floor leveling product but check the square feet to see if the product covers large spaces.

Stores like Home Depot or Ace will have products specifically designed for removing difficult adhesives, but you can also DIY with household products.

A company can go up in value by increasing it's customer base, increasing it's product offering or increasing its prices. 

Biggest thing IMO is getting close to the train station and have a high quality units that may not look attractive on paper the first few years but will have the ability to raise rents consistently long term.