Measured on a resistance or continuity range, a capacitor should read as open circuit with a few seconds, after it has had time to charge to whatever voltage is on the meter leads.
That does not mean it's good, as it could literally be open circuit.
To test a capacitor, you need two things:
A Capacitance meter or capacitance range on a multimeter that has that; it should read somewhere around the marked value, within the tolerance for that type of cap (often quite wide for electrolytics).
And, an ESR meter: That is "quality" test of a capacitor. A high ESR (for the type & value of cap) even with the correct capacitance value means it's failing or failed and needs replacing.
To be fair, you just need an ESR meter - a capacitance meter is fine for checking what value a capacitor is, but not if it's any good or not. Most ESR meters usually display the capacitance anyway, and have the
HUGE advantage that most capacitors can be tested in-circuit.
For any one doing service work, particularly on switch-mode PSU's, an ESR meter is essential - I used my ESR meter at work multiple times every day, and while I'd got a capacitance meter (and actually still have them both) I never found any need to use it, other than trying it out when it first arrived. I was actually given the capacitance meter,where I bought the ESR meter
I'm also a little concerned about the OP's technique - you can't test electrolytics on the ohms range of a multimeter, and certainly not in-circuit. He should be fault finding, not just randomly testing capacitors (or in fact
NOT testing capacitors), and removing them.
As for refitting the capacitor he removed?, doing so without checking it's ESR is fairly pointless, and if he's got one of the correct value he may as well fit a new one, while it's out.
Perhaps if he posted a picture of the board, and explained exactly what's wrong with it, we could offer suggestions?.