So I've downloaded a few a LOT of lots from the Exchange - mostly large ones of castles and palace builds because lately I've developed an obsession with fantasy and medieval themed stuff. As a general rule I try to avoid installing content using the Launcher- I install only Store content and worlds and convert Sims3packs to package files using the Sims3Pack Multi installer whenever possible because it's easier and safer that way. Anyway, I opened up the lots in Sims3pack Cleaner to check for any corrupted things that might crash my game and here's what I've got on basically all of the lots I've downloaded off the Exchange when I open them in Sims3Pack Cleaner(see attachment).
How do I fix this? Are the lots safe to install? Because after I converted the lots to packages they don't look the same in-game as they originally looked in the screenshots

Does it happen with files that you "save as" and files that "add in game"? If you use the "save as", try to "add in game" without installing and see if it's a problem with the downloading?

Crinrict made several posts about corrupt files and Custard:
Corrupt Thumbnails
Corrupt (Not a DBPF) / Bad Download / Bad Index

Also, many lots on the Exchange use Store content, so if it doesn't look like what is in the thumbnails, maybe you're missing some items?

Yes, the corrupt thumbnail files only happen with the files that I use the "save as" feature but does not exist when I download using "add in game". Thanks for the reply