Becca - I work for a large consumer products company, and, yes, we even do have candles. The way I read your question is that you feel you have an off-odor fragrance, and would like to compare to the retain or standard. OK, if that's what you want to do, I'll first tell you what my company would do: simply reject it, as it's off-odor, and that's the supplier's problem, not yours, and it's also not your problem to identify the cause.
That said, we oftentimes do investigate fragrances to find reason for off-odor; we dilute the fragrance oil 1:10 in methanol, use GCMS withsplit injection, starting at 50C, ramping slowly to about 240C. We then overlay/stack and compare suspect fragrance oil to standard, and there can be 75 or more components; our in-house GCMS spectral library enables us to identify components positively. GC-FID can be used similarly, but that doesn't identify the components readily. Yes, we've seen suppliers make errors, such as wrong components or left-over fragrance contamination (this is why GCMS is so valuable, can positively show the non-desired peaks were fragrance components, just had a case like that). If the candles are already made, you're most likely SOL. To compare candles for fragrance, weigh candle into a vial, add solvent such as methanol or DMD, cap securely, heat to melt the candle, shake well, etc., to mix, allow sample to cool so the paraffins kick out of solution, leaving the fragrance soluble in the solvent, then filter and inject that.
