It's slightly confusing... requests to the pool won't be SNAT'd automatically if SNAT is enabled on the pool. It's more that you can prevent a SNAT enabled on the VIP from being used for connections to a specific pool by disabling SNAT on the pool.
The Config Guide has a bit of info on this:
https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip9_3config/BIG_IP_LTM_9_3_Config_Guide-05-1.htmlwp1215931
Allowing SNATs and NATs
When configuring a pool, you can specifically disable any secure network address translations (SNATs) or network address translations (NATs) for any connections that use that pool. You do this by configuring the Allow SNAT and Allow NAT settings. By default, these settings are enabled. You can change this setting on an existing pool by displaying the Properties screen for that pool.
To be honest, I don't use NATs so I'm not sure how a pool would coincide with a NAT. Anyone else have ideas on that one or clarification on the SNAT option for a pool?
Aaron