Clues To Look For Double/Triple Transfers?

I keep looking at all my stamps (revenue and postage) looking for double or triple transfers and can't seem to see them if they are there. Can some of you post examples of what a double transfer looks like compared to a non-double transfer? I'm trying to figure out what they actually look like.
This has probably been covered and if so I apologize, just trying to learn.
Thanks in advance!
dave

Posting a possibility. This R6C looks, where it says "bank check" a lot darker, bolder, than any other R6C's I've got (and I've got 25 on one document to compare to, so I've got a good pool to compare).
What are your thoughts?
Thanks again!
Whole document scan is 300 dpi. Scanning stamp at 1200dpi.

This is one of the smaller of the bank check double transfers. This is a "twisted transfer" type; the bottom left twisted down a bit and the top right twisted up a bit. This stamp plate has a few similar positions.

Thanks RevCollector, I only thought "it looked different" (because I'm not an expert, that's for sure). Good information to have!

The trick is to know what the normal stamp looks like. Years ago (before scanning) I hand traced enlargements of proofs and reduced the tracings to make mats. This gave me a good idea of what should be on a normal stamp. Finding any variation from the normal gives rise to further examination. On most revenues check the corners of the frame, then the four sides,then the lettering for doubling or heavy lines.

Thanks!

Thanks Dan, don't know why I didn't go to your site first. It's awesome!