You apparently don't know the difference between cume and TSL.
Cume has remained relatively constant for the 50 years that Arbitron / Nielsen has been doing ratings.
TSL has declined in the last half-decade. Significantly.
And you apparently don't know what "effective" means to an advertiser. For an advertisement to be considered "effective", it has to result in an increase is sales of the product or service being advertised. The only answers that matters to the question, "Are Spots In Right-Wing Talk Shows Not Effective?" is whether or not the sales of the products or services being advertised on Right-Wing talk shows increased as a result of those spots or not. It doesn't matter how many people tuned in, even if only for a brief period of time. It doesn't matter how many minutes they had their radios turned on, even if only as background noise. All that matters is whether or not the products or services advertised increased their sales or not. In the world of advertising and marketing, that's the only thing that matters.
Cume or TSL describe measurements that are means to an end. Theoretically, the more exposure any advertisement gets, the greater the potential that the sales message carried in the ad will prove effective. But mere exposure alone isn't the only factor. The message communicated must be the right one. It must resonate with the potential buyer, regardless of the venue. It must be able to break through the clutter of other messages. It must be memorable enough to remain in the customer's mind when he is in a position to make the purchase. How many commercials are out there that people remember the joke in the message, but not the name of the product? It must make him want the product. People remembered, "Where's the beef", but it also made many of them dislike all fast food restaurants, including the one that ran the ad.
If a commercial is associated with the host of a radio show, that can be good or bad. People who listen to a host, but who think he's a pompous ass, might not look with favor on any product that he endorses. Even if people like the host, if he has a reputation for a certain flaw, such as obesity, his endorsement of a dining establishment might not be that effective for the establishment.
So, if you want to discuss the topic
Are Spots In Right-Wing Talk Shows Not Effective?, perhaps you should expand your thinking to go beyond the limited issues of cume and TSL and actually give thought to measuring the effectiveness of spots in actually selling products and services.