Every year, new so-called mosquito-repellent solutions appear on the market. All have similarities and differences, the similarity being that all of them are being purchased in huge amounts by consumers. The difference is that some work and some don't.
The fact is that there is little regulation, and manufacturers seem to get away with claiming whatever they fancy, at least as long as nobody's filing complaints. It's not that hard, of course - everybody hates mosquito bites so much that most people are willing to give it a try and spend another $15 on yet another magical repellent solution that just might do the job. If you imagine a new device and can craft a nice story that explains why it should repel mosquitoes, you're apparently on the fast lane to wealth - people will just start buying your product. It's a bit like alternative healing methods - most people don't really believe that they work, but when you're really ill and other methods don't help, why not give it a try? The potential benefit is just so much bigger than the cost. But in the end, most people don't get cured, and most new mosquito repellent devices end up at the back of a drawer.
What have we seen in the past? Chemical lotions (DEET does work, for sure), ultrasonic devices (don't work), amber lights to "scare them away" (don't work - mosquitoes don't see yellow), ultraviolet bug zappers (attract flies but not mosquitoes), vaporizers or mosquito coils (do work, indoors, but they're not very healthy), citronella candles, and so on. Thirty years after the appearance of those useless ultrasonic devices, new variants are still being launched on the market - and bought by consumers, otherwise nobody would keep launching them, right?
Do we need regulation and formal testing, certification and comparisons for each new mosquito-repellent method appearing on the market? Probably not - but it would be good if consumers started collecting more structured feedback on their effectiveness.