Is it normal for BHO to taste harsh?

I made a batch of BHO yesterday. Previously, I had had some mishaps with vacuum pump backflow, and I'm paranoid that some sort of cross contamination occurred. Just to be clear, it did not backflow while purging this batch, but a previous one. I'm worried that I didn't clean my lines well enough.
 
I'm dabbing on my recently cleaned quartz nail and it's definitely not as clean tasting / sweet as my previous batch was. There's this sort of harshness to my throat, it makes me want cough. My first batch made me cough too but it felt different, less harsh. The problem is that I've only ever dabbed my two batches, this one and my first one; I'm inexperienced.
 
My first batch i made using $230 / ounce medical grade OG Kush. The BHO turned out very nice despite having only purged it via hot water. I tasted sweet and citrusy. This batch, I used $200 / ounce bud. It doesn't look nearly as nice, and IIRC it didn't smell as nice either. It tastes weedy and there is a sort of sweetness to it, just it tastes less pure and the unfamiliar harshness makes me worried in the context of my previous vacuum pump mishaps.
 
Simply put, should I be concerned that this batch doesn't taste great? Thanks.

 

nope
 
i had a guy i know whos experienced with bho take a look at it, he said it was alright just a bit overpurged. the nug wasn't the tastiest to begin with

 

or vacced too long. the nug had a brown hue so that's where the colour is from