I've been reading about LLC protections and many sources that seem to be reliable say that a single member LLC is useless and judges pierce the corporate veil on these all the time.

Not possible.The only way to reliably get in touch with motivated sellers is for you to make it easy for them to find you.Get a solid website, work on the 3 pillars of conversions:1.

The contractors I've hired have not been reliable.

As a newbie here, my greatest challenge is consistent, reliable, high quality, detail-oriented cleaning.

Tax Court released Summary Opinion 2017-31 in May 2017, concluding that a county assessor’s allocation to land and improvement values was more reliable than the taxpayer’s proposed values.

Take for instance my B+ located quadraplex consisting of 2 Bedroom units in Philadelphia that rent for just shy of $3,000/m and compare my building to the nearly identical quadraplex building in a C location in Philadelphia were the rents are $1,200/m. 

My instinct tells me yes if I can find quality properties at my price point, but that there could be some benefit to putting it all on one potentially more reliable/higher quality structure. 

Also, if a claim were to be filed won’t the identity of the member(s) be determined through the discovery process?

They're more blue collar and are not always the most reliable if they're too tied up in other projects.

But in any event, that trade-in value will be WAY BELOW top retail dollar he could get if he could afford to list it on cars.com and wait indefinitely to get a top dollar on well maintained, reliable car of the same size and year of make.