I've used the MiniRAE device in about a dozen tournaments now. It's not perfect but it's far better than the methods we used in the past, and overall I'm pretty happy with it. The readings are consistent; for the last three years, every time it's been checked for calibration, I believe it's been spot on. The only failings of the device that I've seen have been the result of user error.
I don't normally carry this thing around to small tournaments. Very few players use high VOC chemicals, and today's rubbers are pretty good without speed glue. But as a player I want to know that my opponents are following the rules - including the equipment rules - so for an honest player, having racket tests is a good thing.
Tournament officials check rackets for other things besides VOCs; in particular thickness and flatness, verifying that the rubber is authorized, making sure the rubber is properly glued and not damaged, etc.
From my experience, the two biggest reasons a racket will be ruled illegal are because of excessive thickness and excessive chemical (VOC) levels. Sometimes this is because a player is trying to cheat by adding chemicals to their rubber. But other times, it's because an honest player made a mistake at some point in preparing his or her racket. I don't think any official wants to throw out an honest player's racket, but the VOC and thickness limits set a firm line that can't be crossed. If a player takes some care in racket choice and assembly, there shouldn't be any problems. You don't need to be obsessive, you just need to know what to watch for.
- Use water based glue. Don't use rubber cement. I still hear older players advise people to use rubber cement for its ease of use and low cost. I've heard of players gluing with rubber cement in training, and then when it's tournament time they reglue the same sheet of rubber with water based glue. This is pointless because all the chemicals from the rubber cement remain in the rubber and wood.
Not only does rubber cement contain illegal VOCs, it can also reduce the play quality of modern rubbers. If you insist on using rubber cement, you may as well use the classic rubbers that were popular in the 80's and 90's because the new rubbers don't work well with rubber cement. The newest high performance rubbers are more sensitive to their environment and rubber cement will often cause them to react poorly; shrinkage is one of the typical indications of damaged rubber. If you can afford today's $60 rubber, you can afford water based glue.
- Use as much glue as necessary to secure the rubber to your blade, but don't build up a massive layer of glue. If your rubber is 4.00 millimeters thick, and you use 0.05 millimeters of glue, that side will be illegal because it's too thick. Now, a responsible manufacturer probably won't sell you rubber that's 4.00 millimeters thick; their "max" offering ought to be thinner than that to provide allowance for glue thickness. But pushing the limit is not to your advantage here.
- Don't play in a tournament using brand new rubber right out of the package. The rubber manufacturing process involves VOCs, but manufacturers are expected to air out the rubbers before packaging and selling them, so in theory using brand new rubber should be okay. Unfortunately, not all manufacturers are diligently airing out every sheet of rubber like they are supposed to. In my own tests, I've opened a few dozen packages of rubber and tested them with the MiniRAE immediately. Only one failed the VOC test, and the one that failed was from a manufacturer that's not known for its quality control. All of the other rubbers I checked, coming from what I consider to be responsible rubber factories, had no problems passing the VOC test. Even so, there is no guarantee that the particular sheet of rubber that you bought is free of VOCs, and it's best to play it safe by letting your rubber air out a bit before using it.
- Pay attention to what else is in your bag. If you have a clean racket and put it in an old racket case that has absorbed chemicals, those chemicals will be transferred to your racket. If your backpack or duffel bag also has other things in it such as chemical sprays or liquids, those things can contaminate your racket.
- Don't use damaged rubber in a tournament. No cracks, no bubbles, no missing pips.
- Use voluntary racket test services. If you wait until match time to find out that your racket is illegal, it may too late. If you have any doubt whatsoever, ask the tournament referee, as he or she has the final authority as to whether your racket is legal or not; it doesn't matter what a previous official at a different tournament told you. If possible, have your racket tested before you warm up, and have your second racket tested as well. If you're a serious player you need a minimum of two rackets, because you'll be using your second racket to practice with while your primary racket is being held at the call area.
Here are two more pieces of advice regarding racket assembly, which probably won't make your racket any more or less legal, but will help maintain it better.
- Don't glue wet. The main component of water based glue is water, so when you're putting glue on your blade, you're spreading water onto it. Then if you immediately put your rubber on the blade with wet glue in between, you're sealing a layer of water into your blade because foam rubber is waterproof. Of course, pouring water onto wood results in softened or rotten wood. So make sure the glue is completely dry before you stick the rubber onto your blade. This leads to the second bit . . .
- Seal your blade. This is not strictly necessary, but I recommend it for the same reason as above. Again, as you're spreading water based glue onto a piece of wood, imagine how the glue will dry. Ideally the water in the glue will evaporate into the air, but bare wood tends to absorb water more quickly than air does, again resulting in soft or rotten wood. So it's best to protect the wood by sealing it. You can tell if your blade is sealed by how quickly glue dries on it - apply glue to both the rubber and the blade, and if the glue dries faster on the wood than on the rubber, that means the wood absorbed liquid and is not sealed.