A buddy of mine uses one and it is effective. Most of your noise will come from buck converters and other cheap power supplies in the near field. Cell phone chargers, 120ac to 12vdc PSU, computer PSU, and fluorescent lighting ballasts are big culprits. Plasma TVs will generate more noise as they age. Pole-mounted cable repeater PSU go bad and start heating up, generating a shitload of noise. Any arcing on cracked insulators will generate RFI and can be easily located by driving around with a clear AM channel on your car stereo. Report these as they must also be repaired. Cheap solar panel inverters are also noise generators. A process of isolating house circuits helps identify the offending devices if they are in the home. In most cases, it is unlawful for devices to generate spurious emissions. In the case of solar panel inverters, they must fix/replace them if you complain. Another thing to check is cable tv leakage, which is less of a problem today, but can still cause interference. Unterminated cable coax can radiate lots of noise in the 144mhz band, and also on other channels. Great article about RFI hunting and elimination: https://www.arrl.org/files/file/RFI/Thompson%20Noise.pdf