It seems anyone could just create a collection in the Steam Workshop for L4D2 and add any items they want to that collection, even if they didn't create the items, and take credit for it, receive raiting and favourite etc.
Most collections have the same items in them, so when you browse through some collections you see the same items over and over again, and you quickly lose interest to browse through the rest of the collections. People comment on the collection pages and the feedback gets all spread out.

Suggestion: When you create a collection you should only be able to add items that you created, no one should be able to create colllections containing items they didn't create. This way we would still have the great collections of campaigns that have been split into parts , but all the unnecessary collections where someone finds every weapon in the Steam Workshop and adds them to a collection would be deleted.

Most collections are items that people want for themselves but these collections are also unnecessary because you can just subscribe/fav and the items stack up in the "Your Favorites" section and the "Subscribed Items" section. And now with proper tags it's easy to find specific items, which makes some collections rather unnecessary. Speaking of tags, there seems to be no limit for how many tags you can choose for your item, so if you for instance create a skin for Rochelle you can have as many as 11 tags such as campaign, survival etc. Some collections only have 1 item, why do we need collections with only 1 item in them when you can just go to the item's real Steam Workshop page and read the description properly etc., the feedback gets spread out.