I constantly reread, tweak and run my reviews through word processing software. I make sure I can read through it at least 3 or 4 times without making ANY changes before I publish it. I also have my man look over them too, because sometimes you read what you think you typed, whereas someone with fresh eyes will read what's actually there.
I'm definitely not perfect, but I try really hard to keep typos and other glitches out of my reviews as much as I can.