As another commenter said, I'd come to the opposite conclusion. I always discount service related complaints as I rarely if ever experience service so bad that I'd not come back. Often you'll see people complain about a long wait or something on the menu not being in stock.

I only look at food quality and restaurant cleanliness reviews and it works out pretty well. If multiple people are saying a place is dirty, I'll avoid it at all costs. People talking about greasy, old... food is also a pass. Most of the time when people complain about service I feel they have weird expectations or lack skills for properly interacting with the staff.