Questo odore è disgustoso.

Because odore is a masculine noun in Italian, even though it ends in -e.

• questo = this, for masculine singular nouns
• questa = this, for feminine singular nouns

So:

• questo odore = this smell
• not questa odore

A useful thing to remember: nouns ending in -e can be either masculine or feminine, so you often have to learn their gender individually.

In Italian, demonstratives like questo often work like this in English and usually replace the article.

So you say:

• questo odore = this smell

not normally:

• il questo odore

The demonstrative already determines the noun, so an extra definite article is usually not used here.

È with an accent is the verb essere in the third person singular: is.

So:

• Questo odore è disgustoso = This smell is disgusting

The accent matters because:

• è = is
• e = and

So without the accent, the meaning would change completely.

Because the adjective has to agree with the noun it describes.

Since odore is masculine singular, the adjective must also be masculine singular:

• odore disgustoso = disgusting smell

Agreement patterns:

• disgustoso = masculine singular
• disgustosa = feminine singular
• disgustosi = masculine plural
• disgustose = feminine plural

Example:

• Questa puzza è disgustosa = This stink is disgusting
  because puzza is feminine.

Yes, odore is a masculine noun.

This is one reason learners cannot rely only on the ending. While many masculine nouns end in -o and many feminine nouns end in -a, nouns ending in -e can go either way.

So it is best to learn nouns together with their article or another agreeing word:

• l’odore
• questo odore
• un odore

All of these help reinforce that odore is masculine.

Normally, no.

With questo, elision is not generally used before a vowel in standard Italian. So the normal form is:

• questo odore

not:

• quest'odore

However, with the feminine form questa, you often do get elision before a vowel:

• questa casa
• quest’acqua

So:

• questo odore = correct
• quest’acqua = correct

Not exactly.

• odore is a neutral word: smell / odor
• profumo usually suggests a pleasant smell
• puzza usually suggests a bad stink

So Questo odore è disgustoso is neutral in structure, but the adjective tells you the smell is bad.

Compare:

• Questo odore è disgustoso = This smell is disgusting
• Questo profumo è meraviglioso = This scent is wonderful
• Che puzza! = What a stink!

Yes, you can say Questo disgustoso odore, but it sounds a bit different.

In Italian, adjectives often come after the noun:

• odore disgustoso

This is the most straightforward, descriptive order.

If you put the adjective before the noun:

• questo disgustoso odore

it can sound more expressive, literary, or emphatic, a bit like this disgusting smell with stronger emotional focus.

So both are possible, but:

• Questo odore è disgustoso = very natural, neutral
• Questo disgustoso odore = more emphatic

A simple pronunciation guide is:

KWE-sto o-DO-re eh dee-sgoo-STO-so

A few notes:

• qu in Italian sounds like kw
• z in disgustoso is pronounced like ts in many accents
• è is an open e sound, like eh
• Italian usually gives clear, full vowel sounds

The stress falls roughly on:

• QUEsto
• oDOre
• disgustOso

In this sentence, you need it if you want to say this smell specifically.

Italian often drops subject pronouns like io, tu, lui, because the verb already shows the person. But questo odore is not just a pronoun—it is the full noun phrase and the thing being talked about.

So:

• È disgustoso = It is disgusting
• Questo odore è disgustoso = This smell is disgusting

The shorter version is possible only if the context already makes it clear what it refers to.

Yes, it is natural and correct.

It sounds like a normal way to comment on an unpleasant smell:

• Questo odore è disgustoso.

Depending on the situation, native speakers might also say things like:

• Che odore disgustoso! = What a disgusting smell!
• Quest’odore fa schifo. = This smell is gross.
• C’è una puzza tremenda. = There’s a terrible stink.

Your sentence is a clear, standard, natural Italian sentence.

The plural would be:

• Questi odori sono disgustosi. = These smells are disgusting.

Here is what changes:

• questo → questi for masculine plural
• odore → odori
• è → sono
• disgustoso → disgustosi

This shows the agreement pattern very clearly across the whole sentence.