[iSnow]

The worst I have seen was a systems biologist flipping between Excel cells with the arrow keys and staring at the Excel input line to find out if sequences are different. My jaw dropped.

[mnw21cam]

There is the story of course of the years of research that were destroyed because some particular gene names looked suspiciously like dates to Excel.

Yes, I was working on a bioinformatics data warehouse a while back. Yes, we did have to write an import filter to extract data from Excel files.