However, if you are going to use the credit card in lieu of being able to actually pay for renovation costs, it can be a terrible plan.

This industry is full of fly-by-nighters who use general estimates and provide terrible deals.

I have flipped over 100 properties and never once even considered tearing a house down, and many have been in terrible shape. 

I know that's not what you're saying but pulling from my own experience I always said flipping is a terrible investment option (Before I knew anything, and I had zero real estate experience).

As long as you understand the neighborhood and what you're getting into, I dont see BRRRRR in a less appealing neighborhood as a terrible thing for long term hold. 

I closed on a terribly mismanaged 8 unit mid April.

(I am also thinking of eventually getting a HELOC on my primary residence, but my understanding is that it's a terrible way to use as a down-payment since the interest is high, unless it can be paid off quickly like in a BRRRR)

Besides charging a lot for repairs ($75 every hour) they have terrible communication. 

So many just read books and sit on the internet, TERRIBLE.  

Sorry for your loss, that is a terrible situation to go through :(I posed a similar question recently as I am in the same situation, lots of equity not being used.