You never feel more prepared for building a house than right after building a house…

Theoretically, this could also work indirectly by improving consulting quality, which increases the likelihood of closing a deal – but in practice, the advised "Dochnichtkäufer" (i.e., those who don't buy anywhere) disrupt this "calculation."

The "Dochnichtkäufer" can be filtered out quite reliably in the first conversation. They don’t get an offer. Why should they?
(By the way, I offer sales training – also for buyers.)

Salespeople who can decide whether someone is a customer or not? Salespeople who only advise promising prospects?

You can find those in the rarity corner, at least in house construction. Many just spout phrases and have hardly any knowledge about the product.

Many knock out phrases and have hardly any knowledge of the product.

That is absolutely correct. Therefore, only buy from a professional and let the "talkers" be exposed. That helps in deciding on a good building partner.

The "non-buyers" can be filtered out quite accurately in the first conversation.

How? Do you have a universally applicable trick for that, which would also work for car salespeople or others, for example?

No "tricks." I'll give three aspects out of many:

[*]Ability to control speaking shares in the conversation. How is a salesperson supposed to learn something about their prospects if only they themselves talk?
[*]Ability to explore conversational and purchasing motives. What does the other party really want? Often even they themselves are not clearly aware of it.
[*]Ability to competently ask goal-oriented questions situationally. No prepared list of questions helps here—if a "trick" is suspected here again.

Even though there is hardly any training for selling—it is a professional business in which many amateurs swarm. Of course, this also applies to car sales and all other industries—whether B2B or B2C.

The salesperson must be an expert in 4 fields:

[*]Customer (their wishes—derived, among other things, from tasks, problems, and goals)
[*]Conversation management (conversation structure, questioning technique, benefit argumentation, handling objections / pretexts, decision support...)
[*]Product & solution (possibly supported by a technical consultant or similar if it becomes very complex)
[*]Self-organization (e.g. not spending time on unsuccessful offers...)