UTM based content spoofing, is it worth it?

Question

HTML

There was an idea to put in the header of the site a substitution of content based on utm tags from contextual advertising.
For greater relevance user queries.
2 sentences of text at the very top of the main page will change.
The only question is, will it hurt search engine optimization? The plans are to do substitution only by utm from direct and adwords, but someone heard from someone that even through the context, substitution can have a bad effect on SEO
. Is this true?

Answer 1

This will not affect search engine optimization in any way.
An example from the life of such a substitution: You go to the store. They ask you "Is there something to show you?". This is the default script of the site script. And if the seller knows in advance that you have come to buy bread, he will ask the question differently, "What kind of bread do you offer?". That is, the essence (an attempt to sell a product) has not changed, only the approach and methods are changing. If you "guess" the client's desire, this will only increase the conversion.
And search robots will only see the default script, since they do not use tags.
This, of course, is meant under ideal conditions.

Answer 2

I don’t understand exactly the harm to seo, but robots don’t index what is added using js by default.
I think if you make 1 option static and two in dynamics, then everything will probably be ok.