I have always been amazed how advertisers use sex in adverting to draw interest to a particular product, such as jeans, for the purpose of sale. So, I googled "jeans adverting".
In both advertising, "sexuality" is used to draw the consumers' attentions on purchasing the products. Along with selling jeans, certain values and attitudes toward sex may be sold.
Calvin Klein uses young models in provocative poses to sell the message to its audience that "wearing jeans is the sexy way to attract opposite sex."
Guess uses young couple to send out message according to the sex-role each plays. In this ad, the man enjoys being dominated.
In both ads, the men are the "ideal boyfriend" who appeals to be muscularly strong and the women are the "ideal girlfriend" who appeals to be sexy-looking and have a perfect-looking body.
I recall back in the 90s when jeans were bigger (Jnco brand) and this trend was used to seemingly advertise comfort and a sense of masculinity in that it was aimed mostly at young men and boys. Times have changed and so has jeans. I agree with you that in the advertisement world, "sex sells." The jeans advertised in these pictures are just part of the bigger view of what the media has deemed to be the "ideal" body. The snug fit of the jeans in these advertisement highlights these curvatures in such a way as to reinforce the heterosexual normativities already in place.
Look how interesting the bottom picture is. There's absolutely no jeans in the ad! I don't know what it's targeting. Woman jeans or man jeans? Well, either one is the same because everyone looks at the ad would think "Okay, Guess' Jeans sells good-looking clothes!". It's a trap!
I have the same point with Eggie. Nowadays, clothing advertisements are focusing on sex which is to attract consumers desires to buy it. In other word, "Sex sells" as Eggie mentions. The images above, I think, do not really focus on jeans but on sex. It's a kind of way arousing people's sexuality to control their desires to buy jeans instead of true selling.