I'm not sure whether they are evil spirits. Some gods
are like humans who have temper. They are also like us, not
enlightened yet. Some "gods" are good and some are evil, some are
petty and easily feel offended. Buddhas and Bodhisattvas are
different from us, they are enlightened.
Don't ask help from "gods" if possible. Their help is only
temporary and sometimes they can't help you at all as they can't
even help themselves. Follow Buddha's teachings, accumulate merits
by doing good deeds sincerely. Doing good deeds may not necessarily
involve money. Like give a helping hand as and when you see someone
in need. By removing a stone on the ground to avoid others from
tripping over it is also a kind of good deeds. Things will go
smoothly once you have accumulate enough merits.
The drinks which mix with the talisman are supposed to bless you
but if you have no merits, nothing can be done to bless you. If you
have merits, you don't need any blessings. Instead of asking gods
or others for blessing, bless yourself by doing good deeds is more
practical and reliable.
I agree, always trust in the law of cause-and-effect. No
matter what is being advertised or promised, however attractive it
is, it can never go against the law of karma. Don't fall into
the sorrow of greed. Even if your wishes may momentarily be
solved but it will not be long-term benefit. I have prayed to
Buddhas and Bodhisattvas for wishes before (not in temple, just in
my own practice). If it is going to be beneficial to you (ie,
help you towards ultimate enlightenment), it will always be
granted. If it is not going to help you, or it is not in line
with your merits, then it will never happen. But in the long
run, you will realise and thank them for not fulfilling your
wishes. That is the beauty of praying to Enlightened
beings.
Other kinds of worldly beings may play with your karma and help
you fulfill some wishes, but as it is just manipulating your karma,
you have to pay the dividend later. It is somewhat like
borrowing from your future to pay your present. Something
like those loan-deriatives that create so much havoc in
stockmarket, all are just like 'flowers in the sky'