So I just bought a pair of Sintechi IDE2SD adapters off eBay, and have been banging my head against a wall for the past few days, trying to get either of the adapters to detect any of my known working SD cards, instead of being picked up by Windows' Disk Management as an "uninitialized" 32MB disk.

I found a Vogons thread mentioning this issue on Google without any answer: Sintechi IDE to SD card - Did not work for me.
So I thought this was an appropriate place to post my solution, to hopefully help anyone who has the same issue.

As it turns out, the contacts on all the SD cards I tried were clean enough to be read fine by my Kingston USB to SD adapter, but it seems the SD2IDE is more sensitive to oxidation/dirt, and there was just enough to cause problems.

My solution: After gently scrubbing all the SD contacts with isopropyl alcohol, a screwdriver and a paper towel, both adapters now detect and read the whole SD card just fine.

Hope this helps someone!