No problems here, and I've ordered several thousand dollars' worth of stuff from Summit over the years. (Ugh ... I'm afraid to ever try to calculate just how many thousands that might be...)
Only packaging problem I've had with anyone was that 50resto.com sent me an incorrect shift knob once, but it all worked out in my favor - they sent me a knob worth twice the one I ordered/paid for, they promptly sent me the right one, and they even let me keep the other knob! (Btw, anyone want a carbon fiber-textured leather 10th Anniversary Cobra shift knob with a 6-speed shift pattern on it? )
I never had a problem with Summit until I ordered a PS92 Crane coil and the package had clearly been opened before and the coil cover was missing and I am not entirely sure that it is a Crane coil (it probably is, but there is no marking to indicate that it is a Crane unit). I did not call them about it because it would be more of a hassle to send it back to get the missing cover and a new coil. I said F_ck it and I will deal with it if it becomes an issue.
I have gotten things from them before that were obvious returns ie: missing parts, opened bags, newspaper packaging. I called them and sent them back and they paid for shipping back to them and back to me. They have awesome customer service. On a side note, they really should check returns better and repack them accordingly.....