I was aware of these limitations. I think they call it "spamming" because if someone is searching for a particular product - "XYZ" - you get to insert your offering into their search results by saying that your is "like XYZ," whereas the searcher is looking for exactly "XYZ."

If you read eBay's explanations, they say that calling something "like XYZ" is too slippery - it's too subjective. There are no standards, and therefore the title "like XYZ" is not a factual or accurate description of what you're selling. (one of eBay's rules is that the title has to accurately describe what you are selling)

Ironically, you can describe something as "not XYZ" and the spam rules don't appear to apply. Thus, I think the problem is the lack of accurate description, rather than the insertion of too many non-specific search results when the searcher is looking for something specific.

I hope this makes sense.