This is kind of difficult to say.
It's going to vary greatly depending on the rating you're talking about. IMO there's no way that a B player can rate an A+ - pro level player. There's a reason that they are a B or below player. Almost every B player that I've ever seen has some fundamental flaw in their stroke or execution, but beyond the mechanics of the game their biggest limiting factor and the biggest limiting factor between low A's and strong A's is their shot selection and decision making process. There's no way that a player who can't understand those subtleties can accurately rate someone. So yeahj if they're a low A to lower rating and it is because of an inability to overcome some physical deficiency and not lack of knowledge, poor shot selection, then yes it is possible they can accurately rate someone higher than them, but otherwise, no WAY in hell.
How do you think hustlers managew to convince people that they are just lucky? and against really good players too. It's because they use subtleties of the game that lesser players aren't aware of. I can jump up on shots, miss every fifth or sixth ball and still win in a match and the person will think I am a lucky B player or that I was off that day and just happened to get some lucky rolls, when in fact I was specifically making shot selections based on liklihood of safetying if I missed etc, that most lesser players just aren't aware of or don't think about.
There are a lot of players who are great shot makers, in fact are as good of shot makers as some of the very best, but it's their knowledge of the strategies and poor shot selection that prevent them from winning. If you go for a shot that is seventy percent for even the best, when you can shoot a shot that is 55% with a 90% chance of a safe if you miss, you've got to know shich one to go for and more importantly, you;ve got to be able to see both shots.
Because this knowledge is really what differentiates most players, there's no way that a lesser player without that knowledge can judge the rating of other players.