Desconfío de esa oferta porque parece demasiado buena para ser verdad.

Spanish often leaves out subject pronouns when the verb form already makes the subject clear.

• desconfío = I distrust / I’m suspicious
• The ending -o tells you the subject is I

So Desconfío de esa oferta is completely natural.
You could say Yo desconfío de esa oferta, but that usually adds emphasis, contrast, or clarification.

Desconfiar de means to distrust, to be suspicious of, or not to trust something or someone.

The preposition de is required with this verb:

• desconfiar de alguien = to distrust someone
• desconfiar de algo = to be suspicious of something

So:

• Desconfío de esa oferta = I’m suspicious of that offer

You cannot normally say desconfío esa oferta.

The accent mark in desconfío shows the stress and also helps indicate that -ío is pronounced in two syllables.

• des-con-fí-o

Without the accent, the pronunciation pattern would be different or unclear. This is a normal spelling feature in many Spanish verb forms where -iar or similar patterns appear.

Both are possible, but they mean different things.

• esta oferta = this offer (closer to the speaker)
• esa oferta = that offer (a bit more distant, or already mentioned)

In this sentence, esa oferta means that offer. It may refer to an offer the speaker is looking at, hearing about, or discussing, but not presenting as especially close.

In Spain, esa is very common for that.

Porque (one word, no accent) means because.

• Desconfío de esa oferta porque... = I distrust that offer because...

Compare:

• porque = because
• por qué = why

Examples:

• No voy porque estoy cansado. = I’m not going because I’m tired.
• ¿Por qué no vas? = Why aren’t you going?

Parece is the he/she/it form of parecer in the present tense.

Here, the subject is esa oferta:

• esa oferta parece... = that offer seems...

So the verb must match oferta, which is third person singular:

• parezco = I seem
• pareces = you seem
• parece = he/she/it seems

Since oferta is the thing that seems too good, parece is correct.

Because buena is an adjective describing oferta, and it must agree with the noun.

• oferta is feminine singular
• so the adjective must also be feminine singular: buena

That gives:

• una oferta buena
• esa oferta parece demasiado buena

Demasiado here works like too, modifying the adjective buena.

Because demasiado means too, while muy means very.

• muy buena = very good
• demasiado buena = too good

The sentence is expressing suspicion: the offer seems so good that it is suspicious, not just very good.

This matches the English idea too good to be true.

Literally, it means to be truth or more naturally to be true.

So:

• demasiado buena para ser verdad = too good to be true

This is a fixed and very common expression in Spanish, just like in English.

You do not translate it word-for-word in normal English, but the parts are:

• para = for / to
• ser = to be
• verdad = truth

Because verdad is a noun, not an adjective here.

• ser verdad = to be true
• literally, to be truth

Spanish commonly uses ser verdad in this expression.
You would not say estar verdad.

Also compare:

• Es verdad. = It’s true.
• No es verdad. = It’s not true.

Yes. Demasiado bueno/a para ser verdad is a very common expression meaning too good to be true.

You can change the gender and number depending on the noun:

• un plan demasiado bueno para ser verdad
• una oferta demasiado buena para ser verdad
• unas condiciones demasiado buenas para ser verdad

It is a very natural phrase for expressing doubt or suspicion.

Yes, and the meaning is similar, but the nuance is slightly different.

• No confío en esa oferta = I don’t trust that offer
• Desconfío de esa oferta = I distrust that offer / I’m suspicious of that offer

Desconfiar de often sounds a bit more actively suspicious.
No confiar en can sound slightly more neutral.

Also note the different prepositions:

• confiar en algo/alguien
• desconfiar de algo/alguien

A very natural English equivalent is:

• I’m suspicious of that offer because it seems too good to be true.

You could also say:

• I don’t trust that offer because it seems too good to be true.

The Spanish structure is very close to the English one:

• Desconfío de esa oferta = I distrust / I’m suspicious of that offer
• porque = because
• parece = it seems
• demasiado buena para ser verdad = too good to be true

Yes. Oferta can mean several related things, depending on context:

• an offer
• a deal
• a special promotion
• a discounted item

So esa oferta could refer to:

• a business proposal
• a sales deal
• an advertisement
• a promotion in a shop or online

In this sentence, the exact meaning depends on context, but the idea is that the speaker thinks it sounds suspiciously attractive.