Are Porcelain Veneers Recommended for Really Crooked Teeth?

If your teeth are "severely" crooked, you may need to see an orthodontist to have them straightened before having porcelain veneers.  You may find that after having them straightened with braces that you no longer have the need for veneers.  Should you still want to have them it would be very easy to do after the braces are removed,  The "preps" would be very conservative and the result should be fantastic.  Good luck whatever you decide. 

If you have super crooked teeth as you've stated, then straighten your teeth out is the priority, then cosmetic fixes.  If you do Invisalign, then you may like that result already and veneers wouldn't be necessary.  I've had patients done Invisalign first and change the shape of their teeth by doing Lumineers.

It is possible to correct crooked teeth with porcelain veneers. However if the degree of crowding is severe enough, there may be a need to straighten the teeth first through orthodontic treatment before undergoing porcelain veneers. A large number of my patients undergo orthodontic treatment prior to placement of the porcelain or dental veneers. This doesn’t necessarily mean braces for 2 years - we can often achieve the desired amount of movement through a relatively short course of Invisalign treatment for example.
 When the teeth are better aligned to begin with, it allows placement of the porcelain veneers without aggressive tooth reduction. It also results in a better aesthetic outcome, as the dental veneers will all be a similar thickness, shape and size.

The short answer is that veneers CAN be put on really crooked teeth but a lot of times this INCREASES the amount of tooth reduction that is necessary.   When teeth are overlapping or flaring it's pretty much impossible to get a good result with veneers without doing some serious modification of your teeth.   If your teeth are really crooked I would recommend doing an accelerated Invisalign movement to at least get you closer to being straight.  Doing veneers on teeth that are 'generally' in the right position increases the esthetic outcome.  They look more natural, the gumline is more precise, they have uniform thickness (or thin-ness).  

If they are extremely crooked, it is best to have them aligned first either with braces or Invisalign. That way if veneers are placed after you will have much better aesthetic results, and you will be able to have more conservative preparations of your teeth, which will be better for you. If they are only slightly crooked then it's possible to proceed with the veneers without orthodontics, but it sounds like in your case orthodontics prior to veneer placement is advised.