Coupling/Headscratchers

In 'The Melty Man Cometh', when dealing with the subject of impotence, Susan claims never to have experienced a 'failure' with a man. Yet her partner, Steve, at exactly the same time is claiming to be a 'follower' of the melty man. So which one is lying?
 * Being a follower of the melty man probably doesn't necessarily mean that it happens every time, or even often. Maybe it just happened a few times.
 * Well during the dialogue, both Steve and Jeff confess their problems. Patrick asks how they ever manage to have sex and Steve replies 'We don't!' which seems to indicate it's happened more than a few times. I still suspect one or other of Steve or Susan are lying.
 * Or (a) Steve was kidding about never having sex, and (b) he'd experienced "meltage" with another woman. He went out with Jane a lot longer than Susan.
 * Well, Jane likewise claims that she's never experienced what the other girls would consider a faillure. Of course, considering her own definition...

Why does "the size of his loneliness" stand out as an unusual thing to say? I did get the Freudian Slip implications, but it does seem if someone being very lonely, using lonliness as a noun, that "size of loneliness" is a legitimate way to say it. (As always, it does keep the show funny.)
 * Mostly while that's plausible, it's also a very unique way to say it. It might just be a little too poetic for characters of their age, upbringing, and education.
 * Thinking about what sounds logically sensible is not a good way to determine what is natural English. Linguists rely on the highly scientific principle of "native speaker intuition", which is literally asking people "does this sound right to you?". Can you actually imagine someone using the words "the size of his loneliness"? Loneliness is an abstract noun, not a concrete one, while "size" is usually used to describe a physical attribute. You might say "depth", or "extent", or "amount", but not "size".

Here's a case of TV Tropes messing with you. After I read the BBC's article that mentioned how tight-fisted they are in regards to avoiding Product Placement, I went back and watched "The Naked Living Room," and in that one episode, I saw Jane holding up a box of Tampax toward the screen, a close up of a Doritos bag Oliver threw away, and a Guiness logo Patrick's glass. I was under the impression that the BBC was a little more strict in regards to even accidental product placement. How'd these get by?