Mutual intelligibility: Italian and Spanish

 
Have you ever thought about how similar some languages sound? Spanish - Portuguese, German - Luxembourgish , English - Scots and son on: there are a lot of languages we can define as mutually intelligible (with different degrees of intelligibility). As an Italian speaker I’ve always felt like Spanish is the easier language to learn for us Italians. Indeed, Italian and Spanish sounds very similar and if you ask to an Italian speaker how close does he feel Spanish , the answer you may get could be “Spanish is easy! It’s just like Italian, but with “s” at end of the words” . First of all, however, let’s briefly see what does mutual intelligibility means.
 
Mutual intelligibility is a characteristic occurring between different languages in which speakers can understand each other without prior knowledge. However, mutual intelligibility can be asymmetric: speaking about romance languages, Portuguese has an high degree of intelligibility with Spanish, but Portuguese speakers understand Spanish better than vice versa. 
 
So, Spanish and Italian have a good degree of intelligibility, and this is also because of the lexical similarity between them:  according to Ethnologue, they have a lexical similarity of 82%. 
 Due to their common origin and geographically position, you can notice that grammar is pretty similar as well.
 
Do you agree, as a Spanish or Italian speaker (or as a student of one of both languages) with the fact that these two languages sounds very similar? As a Spanish speaker can you actually understand to a certain extent a conversation in Italian or vice versa?