I scan the manuals at 300dpi .... not 75dpi like a lot of those on those sites. Then I straighten, crop and in a lot of cases clean up the scans before making a pdf out of them. Also I keep the size of the scans consistent at 1024 x 7xx .....
I started doing this due to the shoddy workmanship on a lot of the N64 manuals on those sites. The only downside of this is my manuals are a fair bit bigger in size compared to the other sites.
Hey ... you don't have to download anything anyway .... and I thought keeping a higher quality differentiates our project from others.
I'm happy to stop doing it if there's no need. It'll save me a heap of time .....