Oracle cloud “always free” tier – can they be trusted?

I initially assumed they would try and trick people into using paid services (e.g. by exceeding bandwith or storage limits), but that doesn't seem to be the case. From what I can gather, you would need to explicitly move into a paid tier.

But... Oracle have a certain reputation as I'm sure everyone here knows. Are there any users who can give me some confidence I'm not going to get hit with a massive bill for accidentally clicking some trivial button?

You're agreeing to get audited by Oracle's lawyers and contacted by their sales just by having an account. Free is too much for doing anything with Oracle, they cannot and should not be trusted.

Trusted to do what?

I feel like “unlimited” anything, isn’t. “Always and forever” means “while it’s convenient”. It’s marketing speak.