I've been a mud fan for 10 years (I'm 20 now). I've played around with small amounts of mud and even had sex with a small amount of clay. each time leaving me with the idea that it is either not enough mud or not dirty enough. being in a city it's difficult finding mud spots that are both deep and private with good consistency.
Yesterday I found my first natural mud pit near a pond. it was about a foot deep, perfect consistency but despite all this, I still didn't find it was as I expected it to be. I'm starting to think that the volume of mud porn I've been seeing in recent times kinda desensitized me to mud. like when I was younger the thought of seeing a girl rub her face in the mud had me stiff as a rock but now that is just to be expected. I think the remedy would be to just stay away from wam for a bit before I go to the pit again. Does anyone else have any similar issues? maybe I'm more into clay?

The fantasy is always different to reality, sometimes in a much better way and sometimes it leaves you wanting.
Try giving the pond a few more goes and see if it works.

As for desensitising- it'll depend on how much porn you use, and whether it's a healthy use or an addictive use.
If you have full control over the urge to watch, and use it to aid/add to the fantasy then you're probably not desensitised- and reality was just different to the fantasy.
If you're regularly getting the uncontrolled urge to watch (or can't do anything else until you do), and when you watch you scroll through content 'grinding it out' until you cum then you may be addicted or desensitised.

(I was in the second category, breaking out of it is hard but life is so much better now.)

I've been getting muddy for 40 years now, and what I've learned is that I won't know how I will feel about it until I get into it.

Sometimes it's relaxing.
Sometimes it's arousing.
Sometimes, I don't feel anything.
Sometimes, I want out of it.

I've learned to just accept whatever feeling I have about it. When I try to force a feeling that isn't there, it doesn't go well. This had led to some frustrations when I've made a trip to get into it and then don't really want to be in it, but I accept that is what happens sometime.

If I have a camera, then even if I'm not into it, I can put myself into the mindset of "well, I'm not really going to enjoy it now, but it's my job to make a video for me to enjoy later", and that has worked well to get something productive out of a trip.

I think it's normal for that heightened level of excitement to subside after a while. The first couple of times I got fully muddy I could cum just by sitting down into it and nowadays it takes a little more doing! Finding different places helps - there can be a lot of variety in look and feel, and the feeling of exploring new spots adds a little something.
I think I have lost a lot of interest in indoor solo gunge or food mess and don't really bother doing that any more, though it's still great when I get a chance to play in it with others. But mud has some sort of special place for me, and even if my horniness level varies, it's always a joy in some way.