Stitchy's got it exactly right, and this is the advice you will get on the thrift thread, too. Almost 0% of my wardrobe (other than unmentionables) was bought retail (unless you count TJX as retail). To be sure, a few things are off by a half inch here or there, but I like to think my eye has improved to the point that I'm generally pretty close. Be ruthlessly honest with yourself about what really fits (lurk here for good examples then emulate), and if you are buying only for yourself (as opposed to for trade/resale), save the money for the items that fit.
It's bad manners to wear a hat indoors and I'm sure the original wearer of that suit would have taken his off once he crossed the threshold.
@ Cliche - Stitchy is handing out some sound advice in his last couple of posts. You say you thrifted some of your threads? Take a look at Pingson's jacket and see how it is an almost perfect fit? THAT is how to thrift my friend!
Applying what I know now, I went home and tried on all the blazers I have and most of them (lets say 75%) are okay with maybe one thing or two things that are slightly off, sadly the others are like this. Hilariously, I just realized that I put on the wrong navy blazer this morning. I bought this one to wear with a sweater. The other one is lighter weight and is a 38 instead of 42 in the shoulders. I'm realistically a 38-40 depending on the cut and the fabric.
In any event, I definitely know what to look for a lot more now and I'm excited to put it all to use.
Thankfully most of the things I own already aren't a huge embarrassment, but are definitely not SF worthy.
Also, if the jacket is a nice fit how much does it typically cost to bring it in a little bit? A few of them are nice enough to invest in a little bit. Otherwise, I just need to be cognizant of the fact that I'm thin and need to pay more attention when I shop for this stuff. I'm well aware of the sunk cost fallacy.
I suppose I can also get measured when there and look at things online as well.