The adult product industry is in a way somewhat seasonal. You'll notice an abundance of new lingerie and toys during the spring and summer months while manufacturers are gearing up for fall trade shows and awards campaigns.
With that in mind, if you see something you want then take a chance and place the order! If it turns out to be a toy that wasn't to your liking, that's an opportunity to write a review and explain why it didn't work for you.
Saying it's really difficult to find an assignment is somewhat about perception. What restrictions have you placed on toys as far as what you will or will not review? Are cock rings and anal plugs out? Don't like realistic toys or you're not a fan of lingerie? Don't use lube? Those things alone significantly narrow the chances of finding something for an assignment.
Not saying that your preferences aren't important, they are but it also helps to go outside of your comfort zone every once in a while. Assignments are great and they are one of the cornerstones of the review program, but there are so many other ways to review items. Buy-outs and points towards the order seem to be forgotten about as if they are an exception and not a viable option on a regular basis. Is this a correct assessment of what's been said thus far? (Feel free to explain if it's not. I'm all ears...err eyes as the case may be.)