They tape ISP networks to detect unusual browsing or unusual traffic.
Some kind of traffic are usually flagged as someone making "illegal stuff" while being perfectly legitimate, such as Tor.
There are many other cases which can be missclassified as "someone is making something nasty" but can be legitimate, or made by someone working on this field.
While what I do is legitimate (I mean, that's my work field), I still prefer to avoid any kind of missclassification by the local intelligence. A VPN is enough for that, they will not investigate to that level any internet traffic, it's more to avoid the automatic detection filters.
A VPS to an other country would be enough too. With a commercial VPN I don't have to maintain the servers myself, I can find other entertaining usages, and I appreciate having a big NAT between me and services I reach.