The key word in that is fan - any fan of anything says it's good. I know people who swear the best food in the world is chilli while others say it's the worst - - while the truth is both are right and wrong at the same time, it's just people have different tastes.
Because this was a hypothetical quote, there is no keyword. When putting this in quotes, I was simply trying to illustrate that if you get into a discussion with most novice authors about their book sales, they will usually give you an excuse that has nothing to do with the quality of their story, or their writing. I have a feeling you missed the point entirely.
Unfortunately, the reason their books are not selling can usually be attributed to one of two things:
1. They haven't developed an audience yet. This not only takes time, but also takes methodology. I will use myself as an example:
When I first began publishing, I did so in the free marketplace using SOL and one other large adult website. I used a couple different pen names for a couple different categories of adult fiction. The nice thing about SOL and other adult story websites is that when you publish the sites audience is automatically made aware of it. On SOL, a new story is listed on the top of the 'new story' page and is also prompted on the homepage. As more stories and posts are added, your story is driven further down on the list, but for the first week or so, you get exposure. As people come to the site, they see your story.
This helps you gain an audience. If people read your story and like the premise, or the writing, there is a chance they will mark you as a 'favorite author'
The paid market is different. It isn't so automatic. If you go into the paid marketplace with the same pen name you used in the free one, you have a definite advantage. If you go about it the right way, some of your fans will follow you from the free marketplace into the paid one. (Assuming they are truly impressed with your writing). But you have to bear in mind that a vast majority of free market readers stay free market readers. Most of them will never pay for materials except for those by authors they already pay for. That's just the reality of it.
But if you do bring a few readers with you, you have an advantage. Getting a few sales from readers when you publish something new will help your books develop connections in the sales algorithms of either Amazon or whatever platform it is on. These connections can lead to additional sales. How ever many sales you get, is the only accurate reflection you have of how big your "fan-base" really is. If you publish a book and make fifty sales, your fan base cannot be any larger than that. Your 'audience' fits into that auditorium.
Your job as an author is to find ways to expand that fan-base. You do this by publishing more works, offering books for free, giving discounts, talking about your books every time you have a chance, or doing whatever else you do as a business man/woman in the publishing industry.
2. Your writing isn't up to snuff.
It only takes one sale to start a book going 'viral'. If you were to write the next 'Harry Potter', 'Fifty Shades of Grey', 'Hunger Games' or whatever floats your book, your explosion would begin after the first sale. All of these books achieved the levels of success that they achieved because the people who bought them loved them so much that they couldn't stop talking about them. They talked about them in person, friend to friend, they talked about them on facebook, twitter, at the mall to the person taking their order, or wherever else they went. That's how going viral works.
There are also different ratios of 'going viral'. Your book can go viral in an explosive way, where you get 3 to five sales for every reader you acquire, or you can have a viral decay model, where you get 1 new reader for every three to five, or even every ten readers who read your book. This is usually more common than viral explosion, but the point is that as your writing or book ideas improve, you will gain more new readers. If you are writing books that people merely like, as opposed to love, or are passionate about, you won't get referrals. Period.
The better your writing is, the more referrals you will get.