Validation is a MUST if OCR is involved, no matter if e-docs or paper docs are processed. For paper docs it is an even bigger must.
Use at least 11pt Arial and render the document as 300 dpi image. This will give you I'd say 99.9% accuracy (that is 1 character in every 1000 missed). Accuracy can drop if you have data where digits and letters are mixed within one word especially 1-I, 0-O, 6-G.
Recognition scripts can be used if you know that you have no such mixed data and OCR still returns mixed digits and letters. You can use the PostRecognition script event to catch the recognition result from the OCR engine and modify it with SBL or VB.NET scripts. But it greatly depends on the documents and data you process.
Image cleanup will not do any good for e-docs.
I'd say your best would be to use validation. At least that will push responsibility to the validation operator.