The study you're referencing makes a solid point - those detectors often don't catch what they claim to catch, especially if someone's actually serious about hiding surveillance. The problem is that legitimate tracking methods (like GPS in your phone or network-based location) aren't necessarily detectable with a handheld gadget. If you're worried about being spied on, throwing a hundred bucks at a detector might feel like you're doing something, but it could just be creating a false sense of security while the actual issue remains.
That said, whether you need one depends on what you're actually concerned about. If you're worried about hidden cameras or listening devices in a room, there are better approaches: checking physical spaces carefully, looking for unfamiliar devices, disabling location services on your phone if you don't need them. If someone has legitimate access to your devices (like a partner with your passwords, or malware), a detector won't help. The real protection comes from keeping your devices physically secure, using strong passwords, being selective about what apps you install, and maybe just not assuming the worst unless you have specific reasons to.
Before spending money, ask yourself what specific threat you're trying to prevent. That'll tell you whether a detector is actually useful for your situation or if your effort would be better spent elsewhere - like reviewing your account security or limiting who has physical access to your devices.
