@Tensoon what do you mean by "spam" here?
Ascii characters, extra information such as character stats etc, indeed pretty much all of your text that appears from the screen comes from the mud not which client you are using. It's generally up to the mud's developer to have alternative display options other than ascii info and ways to control the amount of text you get in the game so that you can keep up with muds action along with sighted players, e.g a way to customise your prompt as I described earlier.
I'll also say that playing some muds, you might need to turn your voice speed up since if your voice is too slow you are more likely to miss things, especially in fast action combat games like cyber assault.
While it is true that if you want to get into more complex scripting there are ways to write scripts for your clients to help with less than accessible muds, eg, by gaggin certain unhelpful incoming text so that it is not shown, generally speaking if you are having to do this just in order to play the game the mud is not truly accessible, which isn't to say you shouldn't play it, just that it will be a lot more work and the developers aren't doing their job properly .
As to vipmud, the differences in the free version are as follows:
1: you can only one session open at a time (though unless your inclined to play multiple muds or multiple characters at once this probably shouldn't matter).
2: If you write scripts you don't get the automatic script debugger in free mode. Again probably only of use if you actually want to start writing mud scripts, plus of course you can write scripts without the auto debugger and check them yourself anyway.
3: In all muds accept Valhalla mud (which David greenwood is a fan of), The free version will cut out after two hours and need to be restarted. While this is mildly inconvenient most muds allow for timed out connections and the like, and if you have created a profile for your mud reconnecting is as simple as opening the program and hitting enter.
4: no msp support. Msp stands for mud sound protocol. This is a way that some developers have implemented sounds in their games by having the mud directly play sound files you've downloaded. This doesn't however mean you get no sounds in the free version, just that you (or someone else), needs to write a script for directly playing sounds as various text gets sent to your computer, rather than be able to use the protocol mud developers setup directly.
In practical terms, there are not that many games that actually use msp (classic six dragons and Materiamagica are the only ones I know and mm's sounds are pretty minimal), and there are several games with very extensive soundpacks scripted directly for Vipmud, ---- Cosmic rage even has an vipmud soundpack written by it's devs.
That is it. Most of the time the only major deal with the free version is the two hour time limit and even that isn't too much of a problem. I personally used the free version of Vipmud (and that back when the time out limit was one hour), for a couple of months and though I did decide to buy the commercial version it was more because I wanted to support Gma games than because I specifically needed the commercial version.
While the conflict of Nvda not reading the headings for text entry boxes automatically is a bit odd, there are several workarounds, the easiest is simply to hit nvda numbpad 7 (in the desktop layout anyway), switch to screen review mode and then hit np7 again to read the headings of the boxes as you tab to them.
Alternatively, you could set the system voice to Sapi and everything reads fine, indeed Vipmud can work entirely through Sapi if you need it to.
Hth.
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)