Barry, short answer:no, long answer:yes.
First things first. Go here
http://www.tone-lizard.com/Tube_Testers.htmland read all about tube testers. Once you do that you will see that, for true mutual conductance type testers, the reading will be either against a gm scale or will be some type of linear scale for that manufacturer. B&K testers, for example, often use a linear scale that goes to 120. There is no real way to correlate the numbers on a B&K tester to the gm number on many of the Hickok testers. Most of the Hickok mutual conductance testers read out on a gm scale (mmhos). Bottom line is you have to know what "good" is for a particular tester. My B&K 707 uses a linear scale, and for most tubes a reading of 65 is considered minimum good. So if someone is selling tubes that test 100/100 on a B&K 707 I would have a good sense that they test pretty darn well.
BTW, when you see two numbers, x/y, that is typical for dual triode tubes. Each number is for a given triode section in that tube. You'd like those two numbers to be usually within 5% of each other for a real nice tube.