Last time we had this discussion (2 years ago), it became very infected eventuelly led to that Mei-Ting and Koji Attwood took off and founded Whitekeys (nowadays a pretty dead site). Lets not hope we end up there again
Regarding professional recordings, you can be very sure that many are modified unless they are live. But not in the case we discuss here. They are not digital rendations or midi modified (of course, I cannot talk for all) but likely copy/paste from different takes. Gould was the first to really make use of the technique but some other famous recordings as for example Pollini's Chopin etudes also used this technique (Pollini's is even bar-by-bar). I think this is the reason why video recordings get more and more popular.
This raises another question. What is most important? That we have a musically good interpretations or that we know that the pianist is capable of playing it?
For us who play the piano, it is rather frustrating that the general public hardly give a damn about who the pianist is. It is the composer and the music that is of highest rank. It is not until you are a frequent listener to classical piano music that you begin to care about different recordings of the same piece and pay attention to who is performing it. For me, it is a combination of the composer's music and the pianist's interpretation that makes the music interesting and I cannot help being a bit disappointed if I learn that a certain recording is bar-by-bar or a digital rendation. It pretty much came as a chock when I learned about Pollini's Chopin etüdes for example. I am always interested in the person behind the recording and his/her thought and ideas about it. This is pretty much what this site is about.
Cheating, well I think it is a different matter from pianist to pianist and how open you are with what you are doing. I do not hide that I use different takes in some recordings to copy everything together into a single track and I did that a lot in some pieces in the Chopin preludes (8, 19 and 24 are the result of 7-10 takes) while most other recordings I have on the site are one take recordings. That is the reason why my output is low. I am a terrible score reader and must learn the piece by heart before I make a recording (that is usually the case). I have experimented a bit with editing programs but find the work utterly boring and I rather spend that time behind the piano keys than with computing programs. But I add a bit stereo effects with my recordings, use equalization and add reverb.
The rules of PianoSociety is that midi rendations must be really something extra to fit on the site and clearly marked. However, it is in some cases very difficult to differ manipulated recordings from one-takes. Especially if you do not provide much information of yourself as a pianist. One cannot help being suspicious when pianists arrive uploading incredible recordings of difficult compositions with no formal piano education or references.