The Marketplace has a great number of assets available to you, and it can sometimes be difficult to decide whether a package is what you require or not. To help you decide, there is a Rating and Comment system in place, where you can see the ratings (from one star to five) that an asset package has and also read the comments made by other users.
When rating a product from the Marketplace, take into consideration not only whether it was useful to you personally, but whether you think it is of use in general too, and also take into account how well it was documented, whether it had extra features or whether you think it was well made or not. Marking something with one star simply because it was not what you expected or don't understand how it works is unfair to the person that uploaded the asset for sale, so try to be just when rating.
The same goes for comments too. If you did not like the asset that you have purchased, or have found a bug or error, then please do not write comments that simply say "this is rubbish" or something similar. Instead, try to leave precise feedback about what you found wrong, or what you didn't like, so that the creator of the assets can consider making changes for future updates.
NOTE: While negative comments have their place and can help, you should not insult or dismiss the creator of the content being commented on, nor insult their product. If you feel so strongly about a listed asset that you want to insult, or are angry, think about flagging the asset itself for YoYo Games to review (see below).
Also comment if you have liked the product and think that it has value to the rest of the community as positive comments are just as important to a developer as negative ones are. The extra support and positive comments will help to encourage them to produce more assets that you and other users can benefit from later.
Note that you can also rate assets from the GameMaker Library, although this does not permit you to make comments on the asset, so you might want to consider taking a moment to go to the actual Marketplace page for the asset instead, as feedback is important!
While browsing Marketplace, you may come across comments that you consider to be offensive or inappropriate. These comments can be flagged as such by clicking on the flag icon to the right of the asset:
You can flag assets for multiple reasons:
You should select the appropriate reason from the drop-down list presented, as well as give a short comment explaining your point of view and reasons.
You can also flag the comments other users have made from the comments section of the asset using the "flag" button:
You can find out more about what is considered acceptable content from the following page: