There is a slight disagreement here between the Greek and Aramaic texts. In Greek, it just uses a derivative of porneia, which means that which is sold (by prostitutes), just like it does in 1 Corinthians 6:9. So the Greek text is always translated as fornicators or the sexually immoral. It is not about prostitutes specifically.
However, in the Aramaic, the word might be slightly more specific. It is walzanayeh. The wa- and -l- pieces are prefixes meaning and for/to, while zanayeh just means prostitute. So literally we have and for/to prostitutes. Everything in Aramaic is derived from verbs (action words), so this literally means someone who goes to prostitutes. In English, such persons are called a whoremongers.
Now, somewhat like in Greek, the Aramaic word for fornication (sexual immorality) is derived from the word for prostitute. So, is the word an expression that means all kinds of sexual immorality, or is it being specific to using a prostitute? It’s difficult to say. The Aramaic translations are split on the matter. The George Lamsa Bible says ‘whoremongers.’ The Murdock translation says the same. However, the Etheridge translation says ‘fornicators.’
It seems that our Ancient Greek translator also thought it implied fornicators, rather than specifically just customers of prostitutes. After all, would visiting a prostitute be wrong, while having sex with a slave be acceptable? Surely both would be wrong. 1 Corinthians 6:18 uses a different version of the same word, and the context makes it clear that we’re talking about more than prostitutes.
However, since we tend to trust the Aramaic, and since it is slightly different to the word used in 1 Corinthians 6:9, in this instance we go with the meaning of whoremongers (or people who use prostitutes). Perhaps the apostle was wishing to be more specific here. After all, the entire list is slightly different to the one in 1 Corinthians. This note should explain that the true meaning might be more broad. Indeed, in 1 Corinthians 6:9, the related Aramaic word zanayeh is translated as sexually immoral.