I don't think something like 'being spoiled' can be seen in a chart, really. It's too subjective, has too flexible an interpretation (of what 'spoiled' means) and depends on outer circumstances, which are never fixed and therefore cannot be read in a chart.
For example: I had two grandmothers, my maternal grandmother, who was very strict but taught me everything I know about how to cook, sew, bake, clean a house spotless AND make a sun hat out of a paper bag (she had an Aquarius moon, okay?
); and my 'mother's boyfriend's mother', who was my other grandma for six years. This second one spoiled me rotten and gave me a sweet tooth to last a lifetime. I got EVERYTHING I wanted from her...but only for six years. How do you find this in a chart?
I think your idea about Jupiter does have some merit, however; although it may not necessarily define 'spoiled', it can certainly point to areas where we have experienced generosity (and possibly excess) in our lives.
For example, I was quite poor as a small child, but my mother became wealthy when I was a teenager: I got a hefty allowance from her, but no time. The 'absent mother' is clearly shown in my chart (Moon conjunct Saturn), as is, perhaps, the strange 'give/not give' relationship I have with her to this day: Moon/Saturn opposes Jupiter in my chart.
Jupiter in the 4th house can show a happy childhood, or a childhood filled with generosity, but again, not necessarily in a material fashion. My son has this placement, and indeed he is showered with love and affection, but he is not indulged, materially or otherwise.
Mr. Archergirl has Jupiter conjunct his Sun, and he is most certainly generous with himself as he purchases a flat-screen TV.
AG