When I said I wanted to waive the "optional" (to the extent that even their own printed paperwork said "not required to rent the vehicle") waivers and reduced/no deductibles (because between my fire/EMS vehicle insurance and credit cards, all their harbingers of doom about how I might not actually be covered weren't applicable), they outright refused.
"No, to reduce fraud if you want to waive our insurance, you actually have to open a claim with your insurer so we know that it will be covered"... Uhh??? Apropos of how nonsensical this is, isn't "opening an insurance claim without an incident sounds kinda ... fraudulent ... to me". "Sorry sir, policy."
Whatever, needed a vehicle, paid the extra, came back the next day to speak to the manager. CSR who was there the day before butted in, "Oh, no sir, you must have misunderstood me!". Outright lies. I was so tempted to send my girlfriend in later to try to catch them out again.
But most of the time, fairly painless. But when not so, then very painful.