I created this table a while back, and I can't recall the source. Maybe it was from Mosher's book, but I made this table so long ago I can't recall where I gathered this from. But here is a link from my website http://www.barleypopmaker.info/guidelinesfordoctoringbeers.docAlso, take a good look at the BJCP website at http:/www.bjcp.org, and go to the exam center section. Even if you are not a homebrewer, if you can hook up with a homebrewing club who is offering a BJCP prep course, they will have doctored beer labs that you can take. Some clubs offer the course without the exam at a lower rate, so it may be worth looking into. You don't need to a be a homebrewer to become a BJCP judge, but it helps because a major part of knowing flaws comes from understanding the brewing process and how specific ingredients affect a beers flavor and aroma.
To start, you may want to do your doctored beers with Bud light or a beer like that. Then as you get used to the flavor and aroma additive, move in to the otherOne last suggestion if you are really getting into evaluating beer, there ar two books you can get for a fair price. THe first is another Randy Mosher book called "tasting beer" and the other is an older judging book simply called "Evaluating beer". Both are good sources for learning about that topic, Mosher's book is much easier to read than the Evaluating beer.I hope that helps you in your quest. Enjoy!