Best way to check for traffic with expired domain names

[wxdqz]

I'm reasonable new to the game of buying and selling domain names, and I was wondering about expired domains.

I'm familiar with the icann dropping, deleting, and auctioning. If the expired domain name is already publicly available for register, what's the best way to check if it has type-in and search engine traffic?

I've seen some domain tools that check alexa, PR, and other things but I'm not sure how to use those to see if it's actually getting a good amount of traffic.

Thanks