Now, I'm not conversant with the workings of UL, to my knowledge they are a test lab only, but, could they bring a case against companies overseas using fraudulent test certifications, especially where their own test certifications are being falsified?
Yes. The UL mark is a registered trademark, and can only be used as authorized by UL. Using it on an unlisted product is an unauthorized use, so UL could file a suit for trademark infringement.