Social history, especially of the late 20th century, is one of the main aspects of the great subject of history that fascinates me the most (the other is the Roman republic, so i have quite a wide area of interest). Adverts are often overlooked as a source material but they can provide an insight into the mundane and the intimate that more "worthy" academic-friendly texts and sources miss.
Take this example of an advert for gas fires from the August 22 1977 Evening Mail (scanned from a reproduction). You can get a lot of information on life in ordinary British homes in the late 1970s. The 1970s aesthetic design of course (though there is nothing wrong with these, the gas fire in my living room right now is listed in this advert!)
The brand names are different, could you imagine someone trying to sell home items branded Radiation these days post-Chernobyl and Fukushima? The prices also show the effect of inflation. £2.25 might get you a thin magazine these days but back in 1977 it was a monthly payment for one of these fires. The total price of £80 and higher might not seem so much these days but back in the late 1970s it was a large amount of money for an average family. In fact the Measuring Worth website estimates that £80 in 1977 is the equivalent of £406 today.
Another thing i noticed was that the advert tells us the hotel has its own motor garage with engineer. Back in the 1920s motor vehicles were a lot less reliable than they are now and road surfaces were not as good. It is likely that many visitors who had come a long way might require their vehicle to have some attention.
We have only skimmed the surface here but these 2 examples of adverts shows the wealth of information that such sources can provide. You could argue (and it is probably true) that none of the information is Earth shattering or vital but they all add to the richness of the picture we build up when examining a period or aspect of the past.