As I said, you have to read them. Some can be tossed out. People downgrade reviews for the dumbest things, like it was not the color they expected or the Ford bumper does not fit my Chevy. I also toss the five stars that say "I got it and it worked great for the five minutes I've used it so far" while the negative reviews state they are bad when the problems showed after repeated use.
The other consideration is common sense. A sub $100 slicer is not going to perform the same as a $3500 real deli slicer, nor would I expect it too. .